When you start thinking of a comforting bowl of tonkotsu, your mind will likely jump the eponymous Tonkotsu, one of London's finest exponents of the umami-laden noodle soup. But now the restaurant's founders have turned their attention to another deeply satisfying Japanese dish: teishoku. Their new site is a Japanese brasserie in St James – co-founder Emma Reynolds tells us why the area isn't as fusty as you'd think, and why it was ready for a casual fine-dining restaurant like Anzu.

How does the concept at Anzu differ to Tsuru and Tonkotsu?

Tsuru is very different to Tonkotsu already. It started years ago. It serves great sushi and katsu and does very well in the city. Then we started Tonkotsu because we thought you couldn't get a really good ramen anywhere in London, so we did some pop ups and that become popular and that's gone really well. It's a dedicated ramen operation.

Emma Reynolds

Emma Reynolds

As for Anzu, it came about partially because we've had lots of recipes in development and we started using more premium ingredients and and ideas that didn't quite fit on the menu at Tonkotsu. We're doing a wagyu steak with soy butter as well as a couple of ramens, and black cod teriyaki and tempura. We're describing it as a Japanese brasserie because it's the kind of food that you'd find in a all-rounder Japanese restaurant. It's a bit more on the finer end of things, given that it's in St James and the ingredients that we're using .

What's teishoku?

Teishoku is going to be a big thing at Anzu. In Japan it’s very common indeed, especially for lunch, and you see it on menus all around the world. You get a rice dish – there's a choice of steamed or takikomi (rice cooked in chicken stock with vegetables ) – pickles, miso soup, and then you choose the main dish from our katsu selection, miso-cured salmon, wagyu with soy butter sauce and various other specials as we roll on.

Is that a food that you'd eat out in Japan or is it something that you'd make at home?

It’s both. Generally people would eat a more varied teishoku selection at home, but smaller dishes of each. It's a really satisfying way to eat because you're getting lots of different flavour sensations. It's quite healthy as well because all the different food groups you're taking in, and eating in smaller amounts. There's lots of umami in there as well.

Why have you decided to open a restaurant that's a bit higher-end?

We’ve been focusing on Tonkotsu and growing that. Ramen is something that's really popular and continues to be, but this is something that's been ready to go on the backburner. This site at The Crown Estates came up and it was something that we wanted to be involved with. It’ll serve as our flagship of the group and we'll use it to do a lot of menu development for dishes that will filter through and that we'll put on at Tonkotsu.

Was there a gap for this kind of restaurant in London?

There are other places in London that are doing a similar thing – I don't know if anybody is doing teishoku – but they always still feel prohibitively expensive. So price-wise, teishoku will start at £15 for lunch, but that's all you'd need to eat for lunch. It's all there. All of our restaurants have been about accessibility and being able to provide the best we can, but for it not to be too expensive. I don't think anywhere is rolling out a really good teishoku, either.

What do you think the challenges will be of opening a restaurant in St James?

We've got new customers who aren't familiar with our brand. We've got Tonkotsus in Notting Hill, Soho and Hackney and they're very, very different crowds each time, and I think St James is going to be the same. I do think the offer and the menu really suit the client base around there. I don't think St James' is as stuffy as its reputation these days. The average age of people who work there is 36. I've got friends who work in private banking and retail around that area, and it has changed a lot. I think that the people there are very much our kind of customer, we might even see them at Tonkotsu in Soho.

How formal will it be?

It won't be tablecloths, but the staff will be uniformed. Casual fine-dining... that's kind of how it works. We want customers to be really comfortable and we want to make Japanese food more accessible because there can still be that formal environment when it comes to Japanese food and in the St James area. So we're going to make it as casual as we can, keeping the service on point.

How authentic is the food?

You’d find everything on the menu in a contemporary Japanese restaurant in Tokyo. We haven't adapted it to suit Londoners' tastes at all. My business partner, Ken, is Japanese, and he's the creative brains behind the menu. His recipes tend to be very much what you'd find in Japan. I don't think you need to do that very much as there are so many Japanese restaurants in London, and there are so many people, especially in St James, who have been to Tokyo and Japan.

Where do you source your Japanese ingredients?

There are so many Japanese restaurants in Europe that there are actually Italian rice companies producing amazing Japanese-style rice. That helps with the air miles – we try to think about all that kind of stuff when sourcing our produce. There are a couple of farmers in the UK that grow a lot of Japanese vegetables now. We'll be sourcing from them, although some of our stuff has to come from Japan and we have to use special importers for that.

What's your favourite dish on the menu?

It's one of the teishokus… sea bass nanban szuke. It’s sea bass that's fried and then covered in soy, mirin, sake and really finely shredded spring onions and vegetables. It's really light and delicious and I'll probably have some sort of rice dish next to that, the takikomi or the steamed rice. It's really satisfying food without being too heavy. I like getting as much flavour into something as you can without it being over the top. I'm not against MSG, but it's not something we do – you have to be able to create that impactful flavour without it being too salty.

Who do you think is doing the most exciting stuff on the London food scene?

Barrafina continues to develop; Som Saa; the guys at Smoking Goat really know what they're doing; and anything Neil Rankin gets involved in. And you can’t beat The Draper’s Arms for a kickass Sunday lunch.

1 Norris Street, SW1Y 4RJ; anzulondon.com