"You can be the bun, I can be the burger, girl. I know you want to do it, we can make sandwiches." No, that isn't a lost verse from Pablo Neruda. Those sweet nothings come from the Detroit Grand Pubahs' sort-of hit 2000 single, 'Sandwiches'. They were recently crooned to me over the phone by Max Halley – author of Max's Sandwich Book, owner of Max's Sandwich Shop, and all-around sandwich obsessive. "I think, like the rest of the world, I've always loved sandwiches," says Halley. His cosy Crouch Hill restaurant is a testament to that affection; a warm and inviting focaccia mecca that opens its doors to London's sandwich fiends, serving them sarnies rammed with everything from soy-braised beef to roasted guinea fowl.

No matter how au fait you may be with early noughties pop music or the London sandwich scene, it's hard to deny that the sandwich has got serious global sex appeal. Or, at the very least, stomach appeal. Sandwiches are an unavoidable part of day-to-day life in the UK – figures from The Guardian suggest that the average Briton will spend £48,339 on sandwiches over the course of a lifetime. And that appetite hasn't shown any signs of relenting.

The UK's 'food-to-go' market has increased by £2.5bn since mid-2015, underlining a growing demand for lunches you can inhale at your desk. A whopping one third of Brits even admit to eating the same lunch every single day.

"I mean, who doesn't love a sandwich, right?", says Missy Flynn, co-founder of deli and sandwich store Bodega Rita's in Coal Drops Yard, and someone who has inadvertently found herself as one of the leading figures in London's achingly trendy sandwich scene. Flynn and partner/chef Gabriel Pryce – whose (now sadly closed) restaurant Rita's created waves in Hackney food circles when it opened in 2013 – have taken the £3 meal deal head-on with their guest chef 'Meal Deal' sandwich series, which allows London's hottest chefs into the kitchen at Bodega Rita's each week to have a go at making their very own stacked sangers. "We've got chefs including Chris Leach, Tomos Parry, and Anaïs van Manen from Bao involved," says Flynn, "I think it's really interesting to see what chefs of that calibre do when given that format."

Missy Flynn of Bodega Rita's
Gabriel Pryce at Bodega Rita's

The format at Bodega Rita's is inspired by the delis and corner stores that you'll find dotted across New York City, serving takeout lunch and sandwiches by day, and mixed drinks and small plates by night. With only four seats inside, the bijou bodega emulates the laid-back vibe of an NYC neighbourhood hotspot. Hefty sandwiches like the Highway Dan (hot bean devilled egg salad with sesame, celery and cress on sourdough) and the Tingler Tower (Szechuan chilli chicken, cucumber, sesame mayo on a brioche bun) offer hungry Londoners respite from tuppaware'd leftovers for lunch. But when exactly did sandwiches become… cool?

"Baking has really taken off in the UK and in London recently," Flynn says when I ask her about the inspiration for Bodega Rita's sandwich-focused menu, "so there's more bread being made than ever – more amazing bread being made, at that – and what do British people do with bread? They make themselves some sandwiches, of course."

In fact, according to the British Sandwich Association, around 11.5 billion sandwiches are consumed in the UK every year, a number which supposedly has the "same environmental impact as eight million cars". Which is, y'know, a lot of sandwich.

Legend has it that the food was first created (and consumed) by John Montagu, the 4th Earl of Sandwich, back in 1762. Montagu was said to have 'invented' the sandwich as a means of keeping his energies up while spending endless nights at the gambling table. I think we can all agree that's a big mood, and that there's no denying Montagu was ahead of the times.

If you're reading this right now, there's a pretty high chance that you've eaten a sandwich of some form in the last 24 hours. You might just be eating one now, like I was, hunched over the counter at Bodega Rita's with a mouthful of mapo tofu. Unless, that is, you're some sort of deranged Atkins acolyte. "It's an interesting time for bakeries here," says Pryce, "because while there's more people interested in being gluten-free who are all about 'healthy eating', at the same rate, people are getting more interested in the quality of the products that they consume." The sandwich isn't just a vessel for cured meats – it's one of the best ways for a chef like Pryce to utilise an artisan product like bread to its greatest potential.

"The bread's really important to the point where, if we've run out of a specific bread, we'll call that sandwich off because it's just not the same without it," says Flynn. Bodega Rita's uses a range of different breads from bakeries all across London, each used in conjunction with a specific sandwich on the menu. As Owen Barratt, co-founder and head chef of iconic reuben-slingers Monty's Deli tells me: "You can right a lot of wrongs with a couple of slices of bread."

You can right a lot of wrongs with a couple of slices of bread

One bakery that Flynn and Pryce are particularly smitten with is The Dusty Knuckle – an East London institution that not only supplies the sourdough for the Baba and the Highway Dan at Bodega Rita's, but also serves its very own door-stop sandwiches. "Their sandwiches are absolutely ridiculous," says Pryce, "but they're so no-frills that they probably wouldn't even care about anyone saying that they're delicious."

Pryce isn't wrong. Rebecca Oliver, co-founder of The Dusty Knuckle, is as no-frills as they come, explaining how the bakery's sandwiches were never a conscious effort to capitalise on any sort of food fad or trend. "We never really make sandwiches thinking about what they deliver on," she says. "We just make delicious food, put it between another thing that we also know how to make well, and then – suddenly – we have quite a nice thing to eat." That description is perhaps the understatement of the year: The Dusty Knuckle's sandwiches are some of the city's finest; hefty two-handers that will give your jaw the most enjoyable workout of its life.

Thanks to their sheer size, there's a nostalgic feel to The Dusty Knuckle's humongous sandwiches – eating one recalls the boa constrictor-like contractions that were required to eat any 'adult-sized' sandwich when I was a youngster. A sandwich is, after all, one of the first things you tend to make as a hungry child (or grievously stoned uni student) raiding the kitchen cupboards.

"I think it's that convenience thing," posits Zijun Meng, chef at Ta Ta Eatery and creator of the restaurant's iconic ibérico pork katsu sando, about the enduring appeal of sandwiches. "When you're growing up and you go to school, what's the most commonly eaten lunch? It's the sandwich." Though the act might have been marred by misogynistic sitcom schlubs, making a sandwich for another person can still be an honest display of love.

A tuna and cucumber sarnie tucked tight into a lunchbox with a packet of Hula Hoops and a Frube wasn't just a balanced meal for me growing up, it was the sandwich of my childhood. It was the reason for the bags under my mum's eyes – that extra half-hour of sleep robbed from her by the drudgery of mixing together skipjack and mayo at five in the morning. It was also the unwavering highlight of every shitty school day: a playground pick-me-up when no-one wanted to talk to me; a welcome respite from mid-set maths; a refusal to cave to crust-less demands, and a constant reminder that my mum cared about my fibre intake.

making a sandwich for another person can still be an honest display of love

Everyone has a sandwich that takes them back. For Max Halley it's a chorizo and coriander number that his mum used to absolutely slather with mayo and butter. The sandwich that most reminds Missy Flynn of childhood is "a white crusty roll with butter and just a slice of cheese" that she'd pick up for 80p from Wimbledon station on the way to school in the morning. A sandwich, after all, isn't always just a sandwich.

"I didn't realise there was this sandwich underworld out there that was so niche but also so wide," says Oliver. Rather than a purely 2019 phenomenon, sandwich safeholds like New York bodegas and Jewish delis in London have been integral to the running of local neighbourhoods and communities for decades. The expropriation of the sandwich by large conglomerates has, unfortunately, somewhat diluted that tradition. "You don't see so many independent sandwich shops any more," laments Owen Barratt of Monty's Deli. "In our case, I think a community has sort of formed around us, rather than us serving an existing one. We do quite a specific thing and not everyone totally gets that they can't come for an egg and cress bun for 40p."

Vada Pao from Koolcha

The Chowpati Vada Pao served at Rohit Ghai's KoolCha 

Food is a focal point for bringing people together, and the innate enjoyment that can be reaped from putting something tasty between two bits of bread is one of the reasons why almost every nation on Earth has got its own take on the sandwich. "The whole world loves them," agrees Alex Fletcher, a man known online as @the.xandwich. Fletcher is an Instagram sandwich influencer (with more than 20,000 followers) who knows his bánh mìs from his bocadillos. "Every culture has their own version. There's something so humble and honest about 'stuff' between bread, whether it's coronation chicken, fish fingers or a pack of ready salted.

Take the Indian vada pao, for example. A deep fried and spiced potato dumpling jammed inside a soft bread bun, it's like the suaver, charming older brother of the chip butty, the kind of sandwich that has tasteful minimalist tattoos and smokes clove cigarettes. The Chowpati Vada Pao served at Rohit Ghai's KoolCha in Boxpark Wembley is one of London's finest takes on the street food specialty: £5 there gets you a crisp and spicy tatty patty nestled in a fluffy bap and finished with fresh tamarind and chutney. "The vada pao is an all-time favourite in India," explains chef Ghai. "It originated as cheap street food in Mumbai, but now it's served in food stalls and restaurants all across the country. I wanted to serve it at KoolCha as it reminds me of my childhood – at school I had it at my lunch break two or three times a week!"

The mapo tofu sandwich at Bodega Rita's is another culturally diverse slapper of a sandwich. Don't just take my word for it, though – according to sandwich tsar Alex Fletcher: "Bodega Rita's is doing it exactly how it should be done". Szechuan mapo tofu, hot pumpkin seeds, crispy shallots and coriander wedged in a fluffy baguettini? You can't go wrong with that. And you can't call it out for cultural appropriation, either. Although it's lacking in the pork department (a traditional ingredient in mapo), the mapo tofu at Bodega Rita's, like Ghai's vada pao, is the real deal.

"The quirk is that it's in a sandwich, it's not that we've messed with it in any other way," says Pryce. "The sauce is made exactly the same way as a traditional mapo with fermented chilli bean paste, black bean paste, and Lao Gan Ma chilli oil. It's essentially how you'd make a really nice mapo tofu, but just put in some bread." That cultural sensitivity and respect for traditional ingredients is just another facet that sets the products at Bodega Rita's apart from the kind of heavily air-quoted 'katsu' sandwich you might find in a high-street retailer like Boots.

But that's not to say all sandwich chains suffer from stale bread and bland fillings. Many sandwich shops that started life as independent stores have started expanding without skimping on quality. Bodega Rita's has plans to develop, at the very least, a second site in London. The reuben at Monty's Deli, with its tang of sauerkraut, mustard, and pickles, has additionally become such a cult sensation in the city that there are now three Monty's dotted across the capital. And the humble sandwich has even managed to wrangle its way into higher-end gastronomy. The bacon sandwich at St John Bread and Wine turns a simple food into the simply spectacular, and the smoked eel sandwich at Quo Vadis? It's a delectable example of how two bits of bread can be sexy.

the smoked eel sandwich at Quo Vadis is a delectable example of how two bits of bread can be sexy

Katsu sandos – in which pork cutlets kissed with tonkatsu sauce are pressed between slices of shokupan (Japanese milk bread) – are also having a bit of a moment in the upscale sandwich scene. The super aesthetic sarnies have become the cult Instagram snap du jour over the last year, so much so that eye-wateringly expensive versions which replace pork with a blushing hunk of wagyu beef have also started to appear on menus, and are duly ordered by snap-happy customers. The singular wagyu katsu sando experience of my life so far came courtesy of an omakase dining experience at a swanky SW3 address alongside some former cast members of Made in Chelsea, which I think tells you all you need to know about just how high the sandwich is punching in 2019.

With that proliferation of Instagram content it does, however, feel like we've hit a katsu sando saturation point. "I think there's no denying that Ta Ta Eatery's ibérico katsu kando is fucking delicious," Pryce told me when I asked him if he'd ever considering whacking a katsu on the Bodega Rita's menu, "but everyone's doing katsu sandwiches now and Ta Ta Eatery stands out in that they're very, very good at what they do. For everyone else it's just like: what's the point?"

View on Instagram

If you come at the king, you best not miss, and Ta Ta Eatery is the undisputed king of the katsu sando in London. The Portuguese-Chinese food concept by Zijun Meng and Ana Gonçalves has had Londoners lining up at every one of its pop-ups and residencies since it started life as a street-food stall at Bermondsey's Druid Street market. Working in Portugal and assaulted by an array of bifanas – a type of Portuguese pork sandwich – on every menu they encountered, Ming and Gonçalves became inspired to attempt their own uniquely Ta Ta take on the sandwich. "We ended up doing a collaboration with a friend of mine at a restaurant called Prado in Lisbon, and we decided it was finally time to bring out our own pork sandwich," says Meng over the phone. "It was based on the idea of the bifana, of course, but the closest thing I could associate with, or what I used as a starting point, was the katsu sando."

Meng and Gonçalves's sando has become the it-girl of culinary Instagram – a milk bread Kate Moss that you can't seem to avoid in overly saturated London foodie circles. Despite its photogenic prowess, though, the sandwich wasn't designed to be an aesthetic object. "Obviously when we do anything food-wise we try to make our presentation as good as possible," says Meng, "but it wasn't something that we designed for Instagram." Thanks to patronage from influencers like Clerkenwell Boy and Alex Fletcher, the popularity of Ta Ta Eatery's sando spread like wildfire. There's admittedly not many restaurants in London capable of charging £14 for a single sandwich, but considering the amount of expensive ibérico pork involved, the price of Meng and Ana's sando isn't anything out of the ordinary.

A man who's similarly working to elevate the sandwich out of the lunch realm and into dinner service is Max Halley. Yes, the very same man you've got to blame for introducing me to the Detroit Grand Pubahs.

Since it opened in 2014, Max's Sandwich Shop has quickly become a must-visit destination for anyone with even a passing interest in eating things between bread. "Before I opened I went round to all the cheffy people I knew and I got them to write down a list of their ten favourite sandwiches," says Halley, over the sound of his bread oven having a bit of a mental breakdown in the background. "Every single one of them consisted of BLT, salt beef, coronation chicken. Even egg and cress and shit like that! I realised, then, that sandwiches were seen as just a lunchtime thing, and that maybe I could turn them into something that you could have as a proper meal for your dinner."

Max Halley

Max Halley of Max's Sandwich Shop 

Just like those served at Max's Sandwich Shop and Monty's Deli, big sandwiches can be big business. Anyone who's ever eaten one of Max's sandwiches will also be able to tell you that they are more than capable of being a 'proper meal'. Or two for that matter. "The Ham, Egg and Chips from Max's Sandwich Shop is the best sandwich I've had," says Monty's co-founder Owen Barratt in praise of Halley's big hitter – a sandwich that delivers on all the textual and flavour components of the iconic British meal of gammon, egg and chips in one hearty bread toddler.

But has Halley ever struggled in convincing people to cough up a tenner for a sandwich? "I mean, have you had one of my sandwiches?!", he exclaims. "They're fucking enormous. They weigh twice what most fucking burgers weigh. At a standard restaurant margin my sandwiches should be about £15 but, luckily for me, we're so busy that we can run at a lower margin than we probably should do. I don't want to have to charge too much for a sandwich."

Indeed, Halley is incredibly keen to keep the accessibility of the sandwich alive, and while you might pay more for a 'This Is How We Spring Roll' at Max's than you would for a £3 meal deal, you get a hell of a lot more out of it, too. As Max puts it, his hand-crafted creations aren't something that need "a bag of crisps and a Coke" to go along with them.

Budget supermarket sandwiches are, in comparison, "pretty much just air" according to Missy Flynn, or "grey air" as Pryce clarifies. That's not to say Flynn isn't partial to the occasional bog-standard tuna mayo when suffering from a particularly achy hangover – the sandwich's reliability, and the fact it doesn't require cutlery or crockery, is one of its major draws. "You should always know what you're going to get and I feel like that's quite an important aspect of the sandwich", says Flynn. "You're emotionally invested and you know exactly what you want out of it."

It's this familiarity that's a big part of the appeal to the people who eat the same lunch-time sarnie every single day. "Nobody sneers at a sandwich," says Barratt, "and no one will call you a snob for eating one."

Needless to say, the sandwich is in a good place right now, but can it continue to keep Britons satisfied, especially at a time when the glut of lunchtime food options continues to expand on the daily? Max Halley suggests a glimpse into the sandwich's prosperous future lies in its past. "Love for the sandwich has never truly abated," he says. "It might occasionally fall a little by the wayside, but I cannot see it going anywhere. I mean, you wouldn't give up breathing, would you?"

British Sandwich Week runs from 19-26 May 2019