The London kosher-restaurant scene has undergone a huge change. Take a trip along the Northern Line and you could stop off at 20 kosher restaurants. In place of traditional Ashkenazi food, you'll now find Persian, Israeli and American.

There is a flower shop selling pizzas and buffets groaning with curries and stir-fries. There's Mediterranean fish and pasta, a pub that does only chicken, steaks cooked on a griddle or served with foie gras - it all sounds good. There are over 100 kosher establishments in London. Boston, in the US, has just six. We should be grateful.

But the fact that we have so much choice does not guarantee quality. So are the restaurants good enough?

For starters

The "best chicken soup in London" has been judged by The Sunday Times to come from a "kosher-style" (treif) eatery. Observant customers seem happy to down a plate of yellow liquid that is far from the flavour-packed treat they serve at home.

The bread, on the other hand, is excellent - rye bread at Blooms, the country loaves at Novellino and the made-in-front-of you pitta at Solly's are perfect for scooping up hummus or chopped liver, or dipping into hearty soups. You might as well linger over the starters: kibbe or chicken wings, aubergine salads and spicy Moroccan cigars. They are often the best part of the meal at kosher restaurants.

The main course

Salt beef used to come with the fat on - a layer of comfort and flavour. The health police have consigned the fat to the bin. In its place is curried chicken or Peking duck. Perhaps through lack of confidence in an increasingly competitive market, owners have turned to Indian and Chinese dishes. t. It's novel and sometimes it succeeds. But fusing two cuisines is surely a mistake: Thai food alongside breakfast pancakes? Chinese and sushi on the same menu? Quantity is no problem. Kosher restaurants tend to follow the "Jewish-mother instinct", so no-one is allowed to leave the table hungry. Portions vary between large and "enough for four". Often the main course comes with salad, chips or rice, squashed on the side - an incongruous mix of cold and crunchy with hot and oily. The meat is usually good; sometimes, as in the case of the 86 Bistro in Hendon or Bevis Marks in the City, good enough for bankers to entertain their clients. The Israeli grills often deliver aroma-filled chops or steak but do not always get the cooking right; they assume that no-one really wants their meat rare.

One restaurant claimed to have a Jewish mama in the kitchen, turning out Iraqi food to be proud of: rice and hameen or a well-judged beetroot sauce. Sadly it went out of business, probably due to a lack of professionalism.

Kosher restaurants employ charming East European waitresses who cannot tell knaidlach from lockshen and find it hard to bring everyone's food at the same time.

The dessert

There are two kitchens that turn out brilliant desserts: Bevis Marks, which performs miracles with parev ingredients, and Novellino, with its professional patisserie. Apart from those, most places offer occasionally good baklava, invariably bad parev ice cream and fruit salad that's dominated by apple and grapes.

If I am hard on the owners and managers, here I think the customers are partly to blame. They are the ones who seem to enjoy a banana split or crème brûlée in which the main ingredient is like white shaving foam.

We are privileged to live in a city with so many supervised restaurants. But we should be more selective and only patronise the ones that offer great service and cuisine. Otherwise, for the same money we could buy several take-aways or treat ourselves to duck or a rib roast and cook it at home