"The only immortality I desire,” Oscar Wilde pronounced, “is to invent a new sauce.” The thought is inspiring. I'd settle for a place marked in history by Sauce Alex, beside Diane and, of course, Mr Lea and Mr Perrins.

But is such a thing possible? Arguably, no world-shaking sauce has been invented since Béarnaise - the gorgeous, velvety coat of semi-set egg yolk, butter, reduced vinegar, shallot and tarragon that is still the best thing you can use to clothe a perfect steak. That appeared in Paris in the 1830s - long before Wilde first sat down to eat at the Hôtel d'Alsace.

The Sauce Age is almost over now, but it was big. The food encyclopaedia Larousse Gastronomique lists about 280 of them. In 1934 the great Auguste Escoffier, “King of Chefs and Chef of Kings”, gave recipes for 102 sauces in his final book, Ma Cuisine. Escoffier wrote confidently: “One must not forget that it is through the subtlety by which our sauces are constructed that the French cuisine enjoys such a worldwide supremacy.”

But classic sauces were already on the way out then. Health worries were beginning to intrude on pleasure, in rich people's food: butter, egg and cream's ancient domination of haute cuisine were coming to an end. As a contemporary food writer said, it was, in 1920s France, “for the first time unfashionable for a successful young man of 30 to be fat”. Refrigeration reduced the need to disguise poor meat and then nouvelle cuisine dealt a death blow to the saucier. Now of course most amateur cooks make a roux about as often as they darn a sock.

My 1966 copy of Constance Spry - the mid-century British housewife's bible - lists 70 or so sauces. Bercy, bigarade, blanche, blonde, bordelaise, runs the index, all the way to sauce verte and sauce vin blanc. There are precise instructions on the four sauces mères, the mother sauces, foundation of them all. “For the student of cookery a knowledge of them is indispensable,” writes Mrs Spry. But can anyone name them now?

Even Delia lists only a dozen or so sauces in her How to Cook, and Anthony Bourdain's cookbook from his classic bistro, Les Halles, gives recipes for only five, Béarnaise, béchamel, gribiche, aioli and crème anglaise. Not even hollandaise, without which boiled asparagus would once have seemed painfully naked.

My mother taught me to make Béarnaise and I'm eternally grateful. She still insists that béchamel - white sauce with a bay leaf or nutmeg to flavour it - is an essential part of cooking and delicious. I suspect that she'd eat it alone on toast. Many people still make it, usually for that classic reduction of Italian peasant's delight into British stodge, Home Counties lasagne.

The other day in a dubious new osteria I found a real horror on the menu - spaghetti carbonara described as “bacon, white sauce and Parmesan”. For this and other insults to good food, I would not include béchamel in my list of endangered sauces that deserve protection. I think life would be good if leeks in white sauce never appeared on a menu again. (Instead try just blanching the leeks and dressing them with sauce gribiche - a gorgeous concoction of chopped egg, olive oil, lemon, onion and capers. E-mail me and I'll send a recipe.)

Could you invent a new sauce? Not easy. Most of the break-out sauce hits of the past century have just been remixes of classics. Coronation chicken is sauced with a curry-flavoured mayonnaise. Paloise is Béarnaise with mint substituted for tarragon. Marie-Rose is, in British catering, ketchup mixed into salad cream. If a new sauce was to emerge it would be found in nut oils and fruit acids and perhaps the fermented sauces of the East. Not in eggs, flour and butter. But there's a challenge - invent a new sauce and we'll give you, if not immortality, at least the space to show it off on this page.

alex.renton@thetimes.co.uk

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