Everyone knows there's fast food or there's healthy food. 'Leon' is a new restaurant concept which challenges that maxim by offering cheap, fast food that isn't bad food. Henry Dimbleby, son of broadcaster Jonathan and cookery writer Josceline, is one of the three Leon founders. He's keenly aware how important Vision's role, in designing and installing all the kitchens, has been to the success of the business thus far and to achieving his huge ambitions.

Can you explain the 'Leon' concept?

We want to make it possible to get away from empty, sugary foods that make you fall asleep in the afternoon and wake up fat. So instead of McBurgers and McChips, there's dishes like grilled chicken with salsa verde, roasted sweet potato falafel, mackerel summer couscous - basically Mediterranean and Meze style dishes. The emphasis is on healthy, seasonal cooking delivered with speed - a fast-food style counter service and cardboard boxes at lunch, then table service and cutlery after 6.30pm. We're big on seasoning, so everything radiates with flavour and, above all, the freshness and vitality of the raw materials. Every ingredient, from the meadow-fresh feta to the golden sesame seeds is high quality and seasonal. The ingredients are occasionally organic; the chicken is freerange; the coffee is ethically traded; many items are low-carb, low-GI, vegetarian-friendly, allergy-friendly, gluten-free, dairy-free, sugar-free - all basically light and healthy.

How many restaurants have you opened so far?

The first came in July 2004 in Carnaby Street, serving 800 covers a day; the second opened just over a year later at Ludgate Circus; the third, this was the Knightsbridge outpost; and the most recent is in Spitalfields Market.

Have Vision done all the kitchens?

Yes, the four restaurants and the 'big kitch' - a central production kitchen where we make all our soups, stews and sauces - the things that require intricate cooking skills get done centrally and then the cooks use them, but also prepare things like salads and wraps locally. We've got a fifth opening now which Vision also planned and installed for us.