Plenty of chefs follow a kind of rags-to-riches trajectory: starting at the bottom, taking abuse, clawing their way to the top via a thick skin and a thin pay packet.

But if you want a true Dick Whittington story, try Thomas Han's. The 30-year-old chef-patron of Dine, which he opened last September in Holborn, came to London from France aged 17, worked in various dead-end jobs, including potwashing, before an interest in food led him to open his own sandwich shop in Bush Hill Park, on the edge of north London, in 1999.

But sandwiches weren't enough, so he sold the business and went back to school - 10 months at the Cordon Bleu. From there he did a year at Chelsea's one-Michelin-starred Roussillon before buying his own wine bar in 2003. But the patrons wanted more sandwiches, so Han decided to relaunch the business as a restaurant.

It worked, and the premier league reviewers have all given Han's gamble the thumbs-up. In particular they've praised his clean and concise pared-down take on fine dining, seasonal and respectful to his ingredients. Not that Han thinks what he does behind the stoves is special. "My food is very classic," he says. "I'm just using ingredients like they've been used by many people before me. They're not my recipes."

Such self-effacement is refreshing, not least because it reinforces the menu's approach to food. On the lunch menu (three courses for £19), hen eggs might be scrambled and served with morels for a starter; while for a main John Dory is accompanied by Jersey royals and wild garlic. As far as his ingredients are concerned, Han just doesn't interfere.

"I want it to look natural, so you can recognise what you're eating", he says. "Sometimes I think the vegetables just look so gorgeous on the stands, it seems a shame even to cut them up into pieces."

The theme continues on the à la carte (still a set price, at £30 for three courses) in starters like strained broad bean and pea soup with morels and asparagus, or an arrangement of "garden vegetables cooked and raw" with crushed herbs. It's also there in a veal chop main served with morels and in the Cornish turbot, bone marrow, English peas and veal jus.

For this dish, Han starts with a 5-6kg fish - "to get nice big steaks" - and pan-fries it with lots of butter. On top goes the bone marrow, poached for about 15 minutes, while the jus is just a very delicate sauce made by colouring veal trimmings, deglazing the pan with water, adding a carrot and an onion and reducing it for about four hours. The only secret? "I add about 500g of butter to half a litre of liquid."

To leave ingredients so unadorned, with no veneer or veil, means getting the freshest produce to start, and Han still makes a point of going to Covent Garden and Billingsgate twice a week. "It's good to pick your own fish, otherwise if it's delivered at 12pm and you're not happy with it, you're stuck," he says.

There are a few curiosities. Sobrassada, a Spanish sausage, is roasted and spread on toast as soldiers, served with soft boiled egg, peas and Indian cress as a starter. For pudding you can choose an orange mirliton, a kind of almond cake, served with crème chibouste.

Currently about 60% of customers take the set menu. The clientele is a mixture of work colleagues enjoying a good value lunch and business lunches. "I'd like to think we can be in both camps," says Han. The restaurant, however, does only about 24 covers. Evenings (the restaurant is open only Monday to Friday) are also pretty quiet, a trend which is worrying Han. "We might do as many as 15," he says. "But we're not making lots of money."

One idea is to launch a vegetarian menu, as an unusual selling point for the City; another is to launch breakfast; Han also might look to add extra tables downstairs. But he's anxious not to upset the balance he's achieved. Even if the streets aren't yet paved with gold, he hasn't become disillusioned.

"We're the same price as people around us, but if you want to compare us, you have to look at the content of the plates," he says. "I don't want to drop my standards. I don't want to start rushing things."

What's on the menu

• Three courses, £30
• Jersey Royal potatoes, lambs' sweetbread, cos lettuce
• Rabbit rillete, country bread toast
• XL Colchester Oyster
• Sand Dover sole, Jersey Royal potatoes, confit tomatoes, fresh herbs, lemon sabayon
• Breast of squab, spring vegetables, tasty juice with offal
• Green risotto, tempura of new-season vegetables
• Roasted banana with rum, light pastry, vanilla cream
• Orange mirliton, crème chibouste
• Bread and butter pudding

Dine, Tooks Court, London EC4A 1LB  Click here for map
Tel: 020 7404 3838
www.dine-restaurant.co.uk