Six years working in Tokyo gave Rainer Becker, a former executive chef at London's Hyatt Carlton Tower hotel, a fascination for Japanese food and culture that has led to him opening his own Japanese restaurant in London's Knightsbridge.

With its layout based on that of a traditional Zen garden, the 130-seat Zuma offers authentic Japanese food with many added elements. For instance, sushi, made in the traditional way, comes with a choice of toppings, such as sweet shrimp (£5.50), scallop (£7.20), fatty tuna (£9.40), sea urchin (£8.80) and Spanish mackerel (£5). Two pieces of sushi are served per portion.

Becker describes Zuma as the UK's only modern izakaya restaurant and robata grill. In Japan, an izakaya is a place where a flow of food and drink circulates the room and stimulates conversation, while a robata grill is based on the age-old tradition among northern Japanese fishermen of cooking over an open fire.

Becker's introduction to Japanese food came in 1988, when he set up the first fusion-style restaurant in his home country of Germany at the Hyatt hotel in Cologne. "I was classically trained in French and German cookery, so learning about Japanese food was a revelation to me," says Becker, whose partners in Zuma are Arjun Waney and Divia Lalvani. Moving as executive chef to the Park Hyatt in Toyko in 1992 enabled him to build on his initial interest. He arrived in London in 1998 to join the Hyatt Carlton Tower, where he was executive chef for two years.

There is no prescribed etiquette about the way dishes are ordered at Zuma, there being no differentiation between starters and main courses. Dishes are generally shared with fellow guests, with a table of four, for instance, selecting around 10 dishes. These are likely to include a couple of salads, some sushi, two or three grilled dishes and some vegetables dishes. The salads include the likes of sautéd mushrooms with butter ponzu jalapeno dressing (£6.50), and crab and avocado salad with soya yuzu pepper dressing (£10.50).

Vegetables, seafood and meat are all cooked on the robata grill in the centre of the restaurant, with the chefs cooking in open view. Among the dishes prepared here are salt-grilled red snapper with lime (£11.50) and organic chargrilled pork ribs with miso jalapeno.

While the same menu is available at both lunch and dinner, there is more demand at lunch for the don dishes (served over a bowl of rice), which each come as a complete meal served with miso soup, salad and pickles. Among the choice of nine such dishes is grilled rare tuna with mitzuba, soy, lime, chilli and garlic sauce (£14.80) and marinated Aylesbury duck with vinegar nashi pear (£16.50).

At dinner, when more individual dishes are ordered, average spend can rise to £60-£70 per head, including drinks. Alongside the wine list, there is a choice of more than 30 sakes, as well as a wide variety of sake cocktails.

Because of the limited selection of desserts in Japanese cuisine, the offering at Zuma is one part of the menu which is not authentically Japanese. Pastry chef Eddy Lee, who is from Singapore, has been given free rein to provide his own selection of sweets. His choice includes caramelised mango and pawpaw gyoza with apricot dip (£7) and sweet dora yaki pancakes with azuki bean paste, berries and almond ice-cream (£6.50).

Zuma, 5 Raphael Street, London SW7 1Dl. Tel: 020 7584 1010. Web: www.zumarestaurant.com.

A selection from the menu at Zuma

On dofu (steamed tofu with chilli and leek confit), £4.50
A-ge watarigani (fried softshell crab with wasabi mayonnaise and mizuna), £7.50
Gyu no tataki (seared beef with soy, garlic, chilli and ginger dressing), £11.50
Sobanomi risotto (buckwheat risotto with wild mushrooms), £12.50
Tai no shioyaki (baked snapper in sea salt, seaweed, garlic and ginger), £16.50
Kamo to sake yaki no houba yaki (sake-marinated duck roasted in hoba leaf), £9.50
Granny Smith sorbet and lychee wine gelée, £5.50
Green tea and banana cake with coconut ice-cream and peanut toffee sauce, £6.50