An hour in the company of Adam Handling is enough to ascertain that you're talking to one of London's most ambitious chefs. Since kissing goodbye to the kitchen at St. Ermin's Hotel, he's made a huge impression on the city's dining scene, first with The Frog E1 in Shoreditch's Old Truman Brewery, and since with the opening of Frog by Adam Handling and his cafés Bean & Wheat, which are designed to not only offer coffee, bread and beer, but to use otherwise wasted food from his restaurant kitchens in light, snacky dishes.

An hour in one of his restaurants is also enough to pick up just how much he enjoys being his own boss, and creating drinking and dining experiences in his own image – literally so, if you walk past the giant portrait of Handling's face in his new bar Iron Stag (which, he points out, he didn't commission personally). In the Frog restaurants in particular, there's a curious blend of in-your-face design and architecture with ambitious, creative cooking, fine-dining elements and impeccable service.

With the contract up on The Frog E1, Handling decided to port the operation up the road to Shoreditch, but to expand on it with the second Bean & Wheat site, as well as downstairs speakeasy-style whisky bar Iron Stag – a continuation of sorts of Frog by Adam Handling's Eve Bar). The result is a fusion of food, drinks, art, design with a theatrical twist and with sustainability at its heart. He fills us in on the scale of the operation, his career landmarks, and closing the loop in his kitchens.

How long were you at the Frog E1 before you branched off with Frog by Adam Handling?

I think it was just over a year [The Frog E1] was open, and then I opened Bean & Wheat, our zero-waste café. And then it was maybe another three or four months after that opened Covent Garden, which is now our flagship restaurant. And then now nine months after that was opened, we've opened The Frog Hoxton, which is going to be our biggest site yet.

What was the reason behind the move to Hoxton from Shoreditch?

The lease was up, it wasn't getting renewed, so it prompted us to do something special and build something which we can make awesome. It was a short-term lease: on a two-year one, you can't really put massive investment into a restaurant when in about a year's time you're gonna be giving it back. So we did it the best we could – we decorated it, we painted it, we made it beautiful – all me and the chefs – and now we have a new restaurant with a 25-year lease, so that's awesome.

the more venues you open, the more you should surround yourself with good people

How are you going to respond to the challenge of operating so many venues? How do you juggle it all?

The more restaurants you open – or even a small project or event – the more everything else will suffer. But the way to counteract that is to hire people around you who are absolutely fantastic. Like Stephen – the group chef, who's been with me 11 years – this guy is the rock of the entire back-of-house. He's a legend. And we've got a lot of chefs that all worked with me before I open I opened E1, created E1, and every one of them is still with me and now they're all senior within the group.

Every time a new place opens or an event happens, one of them will go and do it. I can trust them with everything. So fundamentally, the more places you open, the more you should make sure you surround yourself with good people.

How will the new incarnation of The Frog E1 look?

It's not really just the one restaurant – there's three different outlet on three different streets. On Hoxton Square there's The Frog Hoxton – so that's practically The Frog E1, with a little bit of a facelift, a little bit fine tuning of how we're going to cook, a little bit smarter and a very casual dining experience.

And then inside the same building we have two other entrances in the two other streets: on Old Street, we're going to be doing Bean & Wheat. Whenever we open a restaurant, we're going to open one of them. It will utilise all of our food waste, but fundamentally it's about great coffee, the leftovers from the restaurant used in a nice way, and beer. So using tiny little producers to produce the most fantastic sort of beers, and we'll have a library, so there'll be 200-odd beers there. On tap, the beer there will be produced by the chefs, so Stephen and Johnny, the two chefs, they've got some mad thing about making beer, so they're going be making it and we'll do it there.

And then we're going to be opening on Rufus Street a bar called Iron Stag. It's amazing. It's really, really, really good. It'll have a live jazz area, and cocktails on tap at your tables. We've never done it so over-the-top like this before. Three different outlets in one go is really scary, but the building the way that it is is amazing – you have no idea that it's the one property. It's a little maze inside, but it's our biggest venue yet.

The Frog Hoxton – in pictures

How did the hotel come about?

I got approached by the Cadogan Company, which is a very good family name in Knightsbridge and Chelsea, to ask if I'd be interested in opening a hotel with them or for them. I told them I needed a little more information than that, and it took about six months of chatting, doing proposals – and I wasn't just up against me, I was up against some really big chefs, and when I found out who I was up against, I thought 'to hell with it, we're not getting it, one of these other chefs is going to get it'.

Cadogan have this beautiful building – it's three different buildings in one – one was a hotel where Oscar Wilde used to live; it was Lily Landry's house (the mistress of the king), and it was a bank – so they made it all into one building, gutted it, made it look a little bit traditional in terms of how it originally looked. It's fundamentally a British building and it's lovely.

They approached me to be the restaurant F&B group, and they approached Belmond to be the hotel side of the group, and I thought if I'm teaming up with anyone Belmond is the best one I could be doing it with: they're not so big that it's going to be corporate and scary, and they have a personality as well, Le Manoir is their only one in the UK. So yes, of course, I said I would love to do that. And so anyway the contracts all got signed, and now Adam Handling Restaurant Group is opening a restaurant, a bar, a tea lounge, a private dining room and a hotel. It's going to be exciting. A lot of work.

How is a sustainable ethos instilled across the group?

Our sustainability approach didn't really start off with 'let's save the world'. Nobody can do that. It was done as a business decision. We buy a whole animal, we utilise the whole animal; we buy a whole cauliflower, we utilise the whole cauliflower. We're a tiny restaurant, you have to make as much revenue as possible so that you can pay the staff, get new plates – and then we decided 'let's go a step further and open a cafe'. So we decided to do Bean & Wheat – coffee and bread – and it'll be covered in Kilner jars full of everything that you could possibly think of instead of wasting it.

So as an example, we get mackerel in one day; if we run out of it or we have five portions left and our day boat doesn't have any for the next, what would you do with those five portions of mackerel? We souse them and then put them in little jars. So you've got a tomato compote and then you've got your little pickled or cured mackerel on top of it; you can eat it like that on sourdough.

It's about utilising everything – making kimchi with your outside cauliflower leaves, burning the stalks to make cauliflower puree, and being very smart. And now it's a big thing: we recycle our food waste for our farms, we grow our own vegetables – we're not 100 percent, self-sustainable, because every time you open a restaurant it's real pain trying to make the entire restaurant self-sustainable on its vegetable farms – but we're trying and we really do take that to heart.

What about your partnership with the farm you use?

The farm that we use is called Indie Ecology, and it's great. We make our own food waste into compost, and it's kind of like the circle of life: we have the maximum we get out of a product, food-wise, and then we turn the rest of it into compost to them put on the farms to grow the vegetables.

The guy that we rent on the farms from is a guy called Igor. We're not the only restaurant in London that does works with him – he does it for quite a few – but we rent a really large plot because we've got quite a few restaurants. We work massively with him, a year in advance, with the seeds that we buy and then we just rent the space and work very closely with him about what's growing. I didn't realise celeriac takes nine months to grow, but yet a radish goes up like that. It's about learning about agriculture, learning about what you can really maximise from the seasons, and we do that very well.

Restaurants nowadays have to be smart: you can't survive just serving prime cuts of meat

Do you feel like you're part of a generation of chefs helping to get Britain back to thinking about sustainable agriculture through food?

Britain has always been a powerful country; it's always had so much imported food that it was able to chuck loads of stuff away. I don't want to say we're an arrogant nationality, because I'm British and I love being British, but we had more things than we actually needed and therefore we binned them. But with food prices going up, we can't survive how we used to operate. So it's down to chefs, to restaurants, to people in general, to be smart about what they're doing. The more they're chucking away, the more it's doing damage to the environment, and fundamentally the more the price of food goes up.

Restaurants nowadays have to be smart: you can't be just serving prime cuts of meat and be able to survive having return customers on a weekly basis. £40-50 per person is doable for restaurants that have a return visit, especially in London. Obviously, if you go to a three-star restaurant and you pay hundreds and hundreds of pounds, you can have slightly more wastage. But that's that's a small, small, small percentage and I don't think that will ever change.

It's the restaurants nowadays that are becoming casual dining or even fine dining to a degree but that operator needs to be smart about where their money is going. Rents are going up like crazy, but fundamentally it's about teaching the people below you, teaching your peers, and saying 'you can utilise an entire cauliflower by doing three different things to it'; 'you can utilise a whole lamb instead of just using the prime cuts'. It's just about having respect for the farmers, the products, Britain and yourself.

The Frog Hoxton is open now at 45-47 Hoxton Square, N1 6PD; for more information, go to thefrogrestaurant.com