YOU CAN KEEP April in Paris. Usually it's cold and rainy. I'll take mid-September through the first week or two of October. In that brief period tourists and summer heat are on the wane, yet the gray cloak that covers the sky for much too much of the next six months has yet to appear.

This fall, a brief visit in enchanting weather allowed me to touch base with several landmarks familiar to the food fancier and verify that that praise friends have been lavishing on two of the newer restaurant is justified. Les Halles is indeed gone and the rude shocks of modern architecture that are being sown in the vast space the old central market occupied are obviously intended to wipe out any memory of the old structures, the wonderful array of foods and the colorful people one could observe there without paying any admission charge. At least one monument in the area stands unchanged, however.

Dehilleran, the justly famous cookware supply house on the rue Coquiliere, an easy walk from the Louvre, is as unstylishly cluttered as ever and the clerks are as seemingly unconcerned with events outside or customers inside as they have always been. It is a place for any apprentice gastronome to pass some time, if only to browse. A dictionary of cooking equipment is at hand to look at and touch. If you need help in English, Gaston Number 6 (his clerk's identification) a bearded man whose gruff nature has matured but not mellowed with the years, can provide it. Don't expect him to venture outside his native tongue without prompting, however. Despite the new buildings and inflation, France hasn't changed that much.

Speaking of inflation, a vivid example was provided in a little neighborhood bar-restaurant with ambiance by Formica and perfume by Gaulois. It is called Le Cloche des Halles and can be found a turn to the right and a short block along rue Coquilliere from Dehilleran. Two plates of cold ham (very good ham), three glasses of Chiroubles (very good beujolais), a single slice of an impressionistic version of tarte Tatin (very good, too) and a single small espreso cost $11.

The Place de la Madeleine is a focal point for vistors with a craving for food. There one finds Fauchon and Hediard, which supply so many needs they might be called food department stores; the Mason de Caviar and Lucas-Carton, a dignified temple of gastronomy. A new generation is on the scene, too. Almost next to the Fauchon annex dedicated to pastry, at No.32, the daring nouvelle cuisine chef Michel Guerar has opened his Comptoir Gourmand.

Gerard and his wife, Christine, with their usual flair, have made the Comptoir seem lighter and more informal than Fauchon. Institutions in France (as elsewhere, perhaps) have trouble not taking themselves too seriously and Fauchon is no exception. It's not a question of whether the Guerards' Comptoir is "better" than Fauchon -- it's different. For one thing, the line of frozen "gourmet" foods Guerard has developed is on display and, a clerk told me, selling well. (Fauchon offers some canned foods with a portrait of Guerard's three-star pal, Paul Bocuse.)

The Comptoir also features ham, confit (preserved goose and duck) and foie gras from the Landes, the rural region in far-southwest Frances where the Guerards' spa-restaurant, Les Pres et Les Sources d'Eugenie, is located of more practical value to the traveler -- and less cost -- are a series of flavored mustards and vinegars. With the nouvell cuisine emphasis on grilled or dry-sauteed meats and composed salads, the exotic mustards and vinegars are not just condiments. They have become essential ingredients in some recipes.

Moving around the Madeleine in a counterclockwise direction and into the Rue Royale on your way to the Rue du Faubourg St. Honore, you may discover an alley free of traffic, called the City Berryer. Slip through the gateway and find yourself in an urban neighborhood that seems almost a movie set. Here are food shops for real Paris people -- a greengrocer, a butcher, pastries. And a wine shop, Caves de la Madeleine. it won't take long to realize this isn't an ordinary shop. For one thing, you will quickly spot a lineup of California wines -- cabernet, chardonnay and zinfandel. Secondly, you will find it easy to speak English.

The proprietor, Steven Spurrier, is an Englishman. He has a fine selection of table wines and, even more practical considering U.S. Customs regulations, a superb selection of brandies and alcools blanc such as poire and framboise . These will be several notches in quality above what is sold in airport duty-free shops. They travel well and make gifts that last for some time. The prices here are not modest, but are very fair.

Spurrier has interests in two other enterprises located in the Cite Berryer. One is L'Academie du Vin, which offers lectures and tasting on a regular schedule. Inquire at the wine shop to learn if there is an event and a free place during your stay. The other is a restaurant, Le Moulin du Village. Chef Gerard Coustal's menu is stylishly rustic. Roast beef with ratatouille was a special the day I ate there. I chose instead a terrine of turbot with tarragon, which came with the kind of mayonnaise dressing Kraft can only dream of, and a plate of tender veal slices garnished with with fresh wild mushrooms. The wines are relatively modest origin and therefore not too expensive. During good weather, tables are set outside, a charming idea because there is no automobile traffic whizzing by. Reservations, for lunch at least, are essential. The telephone is 265.80.47

On the Left Bank, close by the Invalides metro stop, Anne Willan was at the reception desk of her cooking school, La Varenne. Upstairs, students were observing a chef prepare tow dishes in classic fashion and, at the same time, with nouvelle cuisine modification. The school makes the most of its small storefront footage in the Rue St. Dominique (No. 34), with kitchens on the ground and first floors. The chef's directions and comments in French were able translated into English by a young intern, a service not always rendered at French cooking classes. The fall term is now in full swing, but one is permitted to attend individual demonstrations if space allows. The telephone at La Varenne is 705.10.16.

For a final meal, or an introductory meal, in this city of restaurants, I strongly recommend Au Trou Gascon, the creation of a brilliamt young chef name Alain Detournier. It is located at 40 Rue Taine in the 12the Arrondissement, a working-class area on the Right Bank beyond the Bastille that has been almost untouched by the architectural changes that have disfigured other neighborhoods. It's quiet in the evening. As you approach, the masked glow of light through the curtained window and the muffled sound of conversation from within are welcoming symbols.

Inside, the place feels like a restaurant should. It's a period piece out of the belle epoque but functional, not cute. Old Armagnacs and jars of preserved cherries are on view, yet the silver is by Christophe and, like many of the most enjoyable restaurants in France, the setting is merely a setting. To find it in such good taste is a plus, but the focal point is the food. In six years, Detournier, who is only 30, has been awarded one star by the "Guide Michelin" and certainly should win a second.

He comes from the Landes and proudly features food products from that region -- wonderful cured ham, foie gras and cured goose meat, duck (crisp duckskin appears in a salad) and farm chickens. There are regional wines, modestly priced, though the cellar has a broad range of bottles from the great vineyards as well. The sommelier is knowledgeable and agreeable and, like the chef, speaks English.

Detournier's cooking is original, light and free of cliche.It helps explain why nouvelle cuisine has a good reputation in France. He has the three essentials this style of cooking demands: talent, enthusiasm and a pasion for first-quality raw materials that doesn't allow for cutting corners.One way to become acquainted with it is to have your party try de Tout Un Peu (a little of everything). The portions are beutifully controlled and the price is something less than $40 per person.

Among the dishes that might appear are a terrine of tiny shrimps with taragon (actually the shrimps provide texture and various vegetables are the features); a spectacular-tasting pattie in which ground meat and fish are wrapped around spinach, which, in turn, encases an oyster; some form of composed salad; rabbit pate with superb onion marmalade; sweetbread nuggets with cauliflower (another salad, warm this time, which may sound mundane until you gather in the collective flavor of orange peel, pistachio, coriander seed and tomatoe).

If these seem esoteric, Detournier does such "basic" preparation as duck with wild mushrooms, chicken sauteed with garlic, fresh foie gras with raspberry vinegar and pork with prunes nanother regional speciality). He once cooked in "the best Chinese restaurant in Munich" and his admiration for Oriental flavorings such as ginger and fresh coriander is readily apparent. Unlike many of his contemporaries, however, he is blessed with a remarkably "true" sense of taste and seasons with a light hand.

The penultimate taste experience at the Trou Gascon should be a sorbet. Flavors such as pear, mango and chocolate suggests themselves without being bidden. The finale should be Armagnac.

Detournier limits himself to about 80 customers a day.Reserve a day or more in advance. The telephone is 344.34.26.