The future may be uncertain for his City clientele, but for the head chef at L'Anima, it's looking very rosy indeed

Out there, it's the City – bleak, cold and windy. Men hurry home with news of cancelled bonuses and stock options, the biting wind a stark reminder of how cold the immediate future could be. Inside, all is warm and light. Jackets are off, yellow ties loosened, blue shirtsleeves rolled up, red braces tweaked, Château Latour poured. It's Thursday night in the City, and the bonhomie volume is turned up in defiance.

It was not my intention to review L'Anima. When Francesco Mazzei opened in June, I was desperate to find restaurants where two could eat for less than £80, not more high-end Italians of the calibre of Locanda Locatelli or the River Café. But in spite of its pre-crunch prices, L'Anima has been hard to ignore: reviews have been practically evangelical, and it was recently named best new restaurant of the year in both Square Meal and the Harden's UK Restaurant Guide.

Most restaurants slipped into the ground floor of a commercial building feel just that, but this minimalist, modern entity completely owns its own space. A buzzy front bar in porphyry and onyx gives energy and spirit to a long, cool, white, low-level dining- room. Designed by London-based architect Claudio Silvestrin and co-owned by the property developer Peter Marano, it is all glass and gloss, accented by limestone floors and a stone and bronze wall, with peek-a-boo windows showcasing the vast, gleaming kitchen, like a Calvin Klein showroom with classy catering.

And classy it is. Calabrian-born Mazzei has ditched the odd Spanish-Italian blend he practised at St Alban, and returned to a purer form of modern Italian that redefines southern Italian classics. Charcoal clams and mussels (£7), lightly redolent of smoke from the hi-tech Josper charcoal oven, are fleshy, briny and luscious, their juices kicked along with a touch of chilli, fennel and garlic.

Pasta here is in a different league to most in Britain, and a small dish of cavatelli with cima di rape (turnip tops), sea urchin and bottarga (dried mullet roe) at £9.75 is proof on a plate. Hand-made, egg-free pasta shells are teamed with soft, tongue-coating flavours, accented with garlic and anchovy.

Wines are an important part of the package, and the list is strong on show-off French and Italians as well as those from sunny Campania, Calabria, Sicily and Sardinia. An oaky, cherry/berry 2006 Ca' dè Rocchi Valpolicella Ripasso Monteré from the Veneto (£29) is well up to Mazzei's involtini di fegato (£21), a plump roll of calf's liver stuffed with pancetta, pork fat, onion and herbs.

It's as good as his version at Alan Yau's short-lived Anda five years ago, this time teamed with pink lobes of kidney, a soft blob of sweetbreads, an amazingly rich olive-oil mash and herby pan juices. A side-dish of deep-fried zucchini sticks (£4.50) adds to the fun, but another of broccoli (£3.50) is dull. A fillet of wild sea bass in the Southern aqua pazza (crazy water) style (£25.50) is less ambitious, the fish simply and gracefully cooked in its light, herby, tomatoey broth.

For pud, a mushroom-shaped babá (£6) is sweet and fragrant with bergamotto, a citrussy Calabrian fruit liqueur, but still too dry to be seductive. No matter, this kitchen sends out more winners than losers. The food has a life and spirit of its own. Like the architecture that frames it, it has pedigree, style and elegance, and wears its strengths – pasta, breads, herby broths – lightly.

L'Anima is not a relaxing restaurant: the floor staff are savvy but distracted – already on to the next thing while still pouring your wine – and the artificial gaiety is distracting; and who knows what the future holds for a restaurant like this, or indeed, for its clientele. But there is no doubt that Francesco Mazzei, like Giorgio Locatelli 10 years ago at Zafferano, is a brilliant star in the making.

16/20

SCORES: 1-9 STAY HOME AND COOK 10-11 NEEDS HELP 12 OK 13 PLEASANT ENOUGH 14 GOOD 15 VERY GOOD 16 CAPABLE OF GREATNESS 17 SPECIAL, CAN’T WAIT TO GO BACK 18 HIGHLY HONOURABLE 19 UNIQUE AND MEMORABLE 20 AS GOOD AS IT GETS

L'Anima, 1 Snowden Street, London EC2, tel: 020 7422 7000 Breakfast, lunch and dinner, Mon-Fri. Around £130 for two including food, wine and service

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