Cultural diversity. Inauthentic cuisines. Queuing. These are a few of the things Brits do. And boy, don't we do them well. In building their mini empire, JKS Restaurants, the Sethi siblings are more than familiar with the same characteristics. There's a strong cultural diversity in the restaurants they manage; they're trying to overcome stigmas attached to inauthentic cuisine; and queuing has become a well-known pastime on London's streets – thanks in no small part to them.

The JKS group comprises restaurants that the Sethis have created – Trishna, Gymkana, and Hoppers – as well as those headed up by the young talent they choose to partner with and, critically, also invest in.

This year, four JKS Restaurants were named in the top 45 in the country by the National Restaurant Awards. In 2014, their Michelin-starred flagship restaurant, Gymkana, was considered by many to be the best in the UK. Some still do. Two Soho street food-inspired ventures – Bao and Hoppers – earned Michelin Bib Gourmands for 2017.

You get the point. The three Sethi siblings – Sunaina, Karam and Jyotin – are restaurateurs at the top of their game. And they're among the youngest, too. According to Karam, who's in his early 30s, that might have something to do with how they got to where they are.

"Our restaurants appeal to the millennial demographic," says Karam, who manages the food side of the enterprise. "The same one all three of us fit in. But that's not to say we open a restaurant for anyone in particular."

"To an extent," adds youngest sibling Sunaina, who's in charge of wine and operations, "you have to share a vision with the people you work with, and who you team up with. The common thing with all the people we've backed, from Bao to Bubbledogs to Lyle's, is the like-mindedness, where they have something we all believe in."

You have to share a vision with the people that you work and team up with… Something you all believe in

As you may have already guessed, one of those common grounds is the appetite for something out of the ordinary. The JKS portfolio has covered a lot of ground in its first year as a collective, encompassing Taiwanese gua bao, Sri Lankan hoppers, contemporary British fare, and a slightly unconventional take on American hotdogs.

"They're restaurants we all want to eat in. And experiences and spaces we think London can benefit from," says Sunaina. "We feel like we can tell a story. With Hoppers for example, Sri Lankan cuisine isn't that well known in London or as accessible in the past, and you might not get a comprehensive understanding of the little places in say Tooting or East Ham. For us to bring that into [central] London, it was almost demystifying it a little bit."

As for keeping the next restaurant diverse but pertinent at the same time, "that's where our biggest effort goes," says Karam. The one with the cheffing background, Karam, develops new menus and concepts, working alongside the head chef of each restaurant to keep what they're doing fresh. When he's not in his whites knocking out some of London's best Indian dishes, that is.

Karam's entrepreneurial mettle was quickly realised in London with his opening of the now Michelin-starred seafood joint Trishna when he was 22. Not long after, he was firing the head chef to assume cooking duties himself. For those that know him, this was hardly surprising (his parents wanted him to be a banker), but if it weren't for his maverick tendencies, perhaps dining out in London wouldn't be quite so exciting.

With Sunaina on the restaurant floor, and Jyotin looking after the accounts (it's great what ten years at Barclays can do for you), you'd do well to find a much more complementary team of people.

"We're lucky," says Sunaina. "Between me and my two brothers, we're quite defined by the roles we've fallen into, because of the skillsets each of us has. When opening a restaurant, I'll lead on the front of house and operations, with Karam on the kitchen side, with my elder brother [Jyotin] telling us not to spend too much money."

There's no switching off, because its an obsession for each of us

It should go without saying that starting up any business is a stressful experience. But that doesn't compare to what it's like when your siblings are involved. "Work never stops," says Sunaina. "Whenever we're together, we're always talking about food and restaurants. And restaurants, and restaurants. There's no switching off because for each of us it's become an obsession.

"On the positive side, you get things done so much quicker, and ultimately you do have the same end goal. Even if that means shouting and screaming at each other. In a way you don't have to be as diplomatic as you would with non-family members – we tend to get to the point a lot quicker."

With all the expertise in the room, those running the subsidiary restaurants certainly aren't any worse off either. As a trained sommelier, Sunaina makes sure the wine lists are all on point. Though it can't be the easiest job when you're tasked with matching Taiwanese gua bao or traditional Indian chatpata to an appropriate vino.

"Generally speaking, Italian wines go well with Italian food, and French wines go well with French food. With Bao I worked with Wai-Ting, who looks after operations there, and we did the wine list together. I think what's important is when I'm not on site, she understands the thought process behind the wine so she can pass that on to staff."

Even with her obvious enthusiasm for wine (she indulges me on her adventures unearthing some esoteric Polish and Croatian varieties), Sunaina suggests passing on knowledge is definitely a two-way road. "Sandia at Bubbledogs? I can learn a lot from her when it comes to champagne."

Dishes at Michelin-starred Gymkhana

Dishes at Michelin-starred Gymkhana

Spend ten minutes talking to a Sethi and you very much get the impression that they're thinking about what's next on the boil. Their latest project – Motu in Battersea– is what we've come to expect; that is, not something they've attempted before. You could describe their most recent venture as similar to an Indian takeaway, only more bona fide than the kind that we're used to.

"It'll be indulgent home-style Indian food. We'll be giving the customer the compete meal, packaged really nicely, with food cooked to the standard you'd find in our restaurants," says Karam. "You order what we're calling a Feast Box – choose your curry, or biryani or mixed grill. Then three sides – naan, pilau, chutney. And then the dessert."

The kitchen will be based in Battersea, and with the help of Deliveroo will deliver only to Chelsea, Fulham, Wandsworth, and also to some areas of Putney. "Ideally we'll open more than one if liked by the public and the system works," says Karam.

Seeing as much of the Sethis' success is down to predicting the next big thing, and seeing as they've yet to get it wrong, I ask Karam what London'll next go weak at the knees for.

"Ethnic cuisine," he says. "Everything from southeast Asian to more regional Asian, which is the more exciting thing for me. I went to Kiln [the new sister restaurant to Smoking Goat] the other day, which is bloody good. The quality of the produce, the punchiness of the cuisine, in a great vibe-y environment. That whole style very much fits, in my mind, with the perfect current day restaurant." Who am I to argue with that?