FOUR WHITE muslin bags hang in the wine cellar of the French Embassy, along with two long rolls of bacon tied with twine. Francis Leyerle has been at it again, salting and herbing and hanging his own hams and bacon to cure, since he cannot import them from France.

In the back of the residence is Chef Leyerle's garden--with tomatoes ripening and tarragon, basil, thyme, mint and oregano ready to snip. On the kitchen's shelves are his cherries pickled in honey vinegar and the jelly he made from red currants he found in the York, Pa., market last summer. In the refrigerator rests Leyerle's own goat cheese, made from milk brought by a man who travels from Strasburg, Va., every Thursday with squab, rabbits, baby lamb, farm-fresh eggs and the pork Leyerle uses for curing. On Tuesdays the herb man drops by with the purslane and sorrel.

Washington isn't Gascony when it comes to culinary resources, but Leyerle has gone to great lengths to reproduce the larder of his native region in southwest France. Downstairs he carries on the traditions of Masseube, the tiny village near Auch where he was born. Upstairs the embassy guests talk of the new, fresh, light and inventive cuisine Leyerle fashions from those traditions.

But this wiry, impish-looking, curly-haired young man doesn't look old enough to have spent eight years as a chef at the French Embassy. And truth to tell, he hardly is. He was only 21 when he was hired as sous chef straight from the army, where he had been cooking for the soldiers for two months, the generals for four months, and then became sick--from eating too many oysters, which one supposes could only happen in the French army. As soon as he arrived in Washington, the soft-spoken Leyerle began practicing his English by playing rugby with students from Johns Hopkins' School of Advanced International Studies.

While progressing through all the usual apprenticeships of a French chef, Leyerle had been administered a strong dose of earthy tradition; he grew up cooking with his grandmother in the foie gras and confit center of France, and detoured to Alsace, where for three months he made at least 100 pounds of sauerkraut a day. That hearty base shows in the calves' feet he adds to give body to his chicken consomme', in the turnips he simmers under a parchment cover until they melt on the tongue. But the final product is as delicate as a Japanese brush painting. Seafood becomes pale pink "zephyrs of lobster." Snow peas are painstakingly split--not quite to the stem--and fanned out on the plate. Corn leaves the cob for tiny boat-shaped pastries. And dinner at the French Embassy has been pared to a mere three or four courses, with rarely a cheese course. One guest last winter reported that the meal was so light that a waiter whispered to him to take a lot of it.

That suits the new ambassador, Bernard Vernier-Palliez, and his wife, Denise. She is Parisian, but has spent much time in the south of France and favors "new style" cuisine. As she plans menus with Leyerle, Denise Vernier-Palliez aims for lightness and restraint and tries to have "not too much cream." She also prefers the dining room set with several small tables rather than one large one, and the food arranged on buffets so that people can circulate and talk. "I try sometimes to manage the menus so that only one wine will be used," she adds.

Few changes show in the kitchen with this new administration, though Leyerle says there are more stag lunches and "a lot of society dinners. She knows a lot about food," Leyerle says, and Vernier-Palliez's taste is reflected in the menus. While the embassy imports turbot and Norwegian salmon, "She loves the fish here--sea bass, red snapper, pompano." The new ambassador's wife adds that she is particularly looking forward to vacationing in Maine to take full advantage of the "superb" American lobsters. Serving lobster is affordable here, she explains; "In France it is out of the question."

Among the few culinary changes with this administration are one predictable shift and one surprise: "Caviar we never serve," says Vernier-Palliez, except the cheaper American golden caviar; what else would one expect in these times? But veal, as fashionable in Washington as fur coats and cowboy boots, is also disappearing from the embassy's menus. "I always think it is a bit tasteless," says Vernier-Palliez, who greatly prefers lamb.

Thus, a recent menu--one grand enough to warrant three wines--consisted of cold consomme' with chervil, zephyrs of lobster with parsley and saddle of lamb with turnips, with no cheese or salad intermediary before dessert. Another three-wine menu progressed from a mousseline of salmon with champagne, to duck breast, to a chestnut dessert in a thin cookie shell. Or there might be lobster consomme', pigeon and a caramelized almond dessert. Nothing American, of course. American wines? "No, never," declares Vernier-Palliez. She does serve rum after dinner along with the cognac, explaining that her nephew is a director of the Cointreau company, which produces the St. James rum she has stocked in the cellar. But in her short stay in the United States she has yet to even taste much American food. "Virginia ham with pineapple--that I never had," said Vernier-Palliez. Nor has she had fried chicken. Or cheesecake. "I love cheesecake. And I was never served cheesecake anywhere."

But running an embassy that entertains every day leaves little time for searching out American specialties. While very large dinners are limited to no more than one a month, dinners for 25 are scheduled frequently, in addition to breakfast and lunch.

"Sometimes it is hectic and sometimes it is quiet, but it is never dull," says Desoline Bacher, the embassy's social secretary who has been posted here for 31 years. "Usually it is chic," she declares, adding that the kitchen is improving all the time.

She refers, of course, to the food rather than to the kitchen itself, an ochre-colored room that looks typical of those designed four decades ago. It is equipped with two telephones and a dumbwaiter but no dishwasher. Leyerle works with one assistant, Marie-Elena Mendueri, both bustling at top speed in near silence.

Leyerle's menus are deceptive. For the three courses he has planned, he may have four saddles of lamb in the oven, turnips simmering in a copper pan and pots warming glazed potato balls and cherry tomatoes, green parsley sauce, turnip sauce and water for the green beans. One bowl holds mushrooms, another watercress and a third chopped parsley. The platter of meat will be garnished with five to seven different vegetables. A peppery golden consomme' jells in the refrigerator, to be garnished with carrot flowers, chopped tomatoes and a single asparagus tip. Tuiles are piled in a dehumidified pantry; plates are set with truffle slices, corn barquettes and split snow peas. On long buttered silver platters pink mousses of lobster are lined up, ready to be spooned with the green sauce. Lime and watermelon sherbet, made just hours before, is in the freezer, ready to be scooped into a watermelon shell, sauced with lime syrup and garnished with shredded lime peel.

Leyerle departs from the new style in preferring to serve food from platters rather than preplated. Waiters line up for the platters, carrying them upstairs. The emptied platters and floral Sevres china, made only for the embassy but similar to that of the Elysee Palace, are returned by dumbwaiter, to be washed by hand. Glasses and crystal fingerbowls--which are afloat with salmon-colored rose petals--are washed in an upstairs dishwasher. The pace of the meal is signaled by buzzer: One buzz means that the waiters have changed the plates, two that they are ready for the next course.

The embassy, with eight guest rooms, depends on the kitchen from morning croissants--served on silver trays with fresh orange juice and the best English or Indian tea--to lunches, to afternoon wine tastings or parties given at the embassy by French-oriented organizations, to grand dinners. But never more than today, when 1,500 Bastille Day guests will nibble Leyerle's homemade garlic sausage in brioche, ga teau opera, lemon tarts, strawberry tarts, tiny pithiviers, champagne and vin de dieu--a punch of red wine, Cointreau, orange slices and mint--from Leyerle's garden, of course.

Chestnuts are out of season, sweetbreads are difficult to acquire, and consomme' is an all-day project. Culled from Leyerle's favorite recipes, here are some that are practical for an American kitchen with no ready source of Bayonne ham or foie gras. First, some ideas for hors d'oeuvres: FRANCIS LEYERLE'S HORS D'OEUVRES

* Dense rye bread, preferably homemade, trimmed of crusts and cut into triangles, spread lightly with butter seasoned with minced shallots and vermouth or with lime, then spread with a thin, even layer of golden caviar.

* Small rectangles of crustless bread topped with smoked eel and piped with mayonnaise, then sprinkled with snipped chives.

* Fresh smelts dipped in tempura batter and fried, with a sauce of sour cream, whipped cream and chives.

* Very thinly sliced raw filet of beef layered in a terrine with anchovy butter, then weighted down. To serve, the terrine is cut into narrow slices, as for pa te', so that the paper-thin layers are revealed.

* Rectangles of crustless bread thinly spread with anchovy butter and topped with a paper-thin slice of raw beef, then lightly sprinkled with coarse salt.

* Raw asparagus tips cut to 2-inch lengths, then split lengthwise into two or three slices, set on bread cut to the same size and lightly spread with watercress butter. SIMPLE FRUIT DESSERTS

* A peeled orange, with pith removed and sections arranged like a flower on a dessert plate, drizzled with 1 teaspoon grenadine syrup, garnished with mint leaves and surrounded with raspberries.

* Cantaloupe or honeydew melon scooped into balls and arranged on dessert plates, sprinkled lightly with freshly ground pepper and topped with red currants. GRATIN DE LAPEREAU AU BASILIC (Rack of Rabbit with Basil Sauce) (4 servings) 2 racks of rabbit 1 carrot, diced 1 small onion, diced 1/2 leek, diced 1 stalk celery, diced 5 leaves basil, minced Salt and pepper to taste 1 tablespoon butter Sauce: 1 1/2 cups whipping cream 1/2 cup bouillon 1/2 teaspoon minced basil

In a heavy, covered pan over moderate heat, cook the rabbit with the carrots, onion, leek, celery, minced basil, salt, pepper and butter, for 5 minutes or until meat is just slightly pink. Remove rabbit from the pan, bone it and set it aside, covered, to keep warm while you make the sauce. To the pan, add 1 cup of the cream and 1/2 cup bouillon, and boil until it reduces and thickens to a sauce. Strain sauce and set aside. Cut the rabbit into fine slices and arrange on a warmed heatproof platter. Whip the remaining 1/2 cup cream and fold it and 1/2 teaspoon basil into the sauce. Cover the slices of rabbit with the sauce and slide under the broiler until lightly browned. Serve immediately.

The rest of the rabbit can be put to good use in a pa te' or terrine or stewed with white wine, or just saute'ed with sherry. SALMON MARINE AU LIME (Salmon Marinated with Lime) (1 serving) Salt and pepper Paper-thin slices of salmon, to cover plate 1/2 lime 1 tablespoon olive oil Bread for serving

Sprinkle a small plate with a pinch of salt and pepper. Cut raw salmon into paper-thin slices and arrange on the plate. Salt and pepper it lightly, then squeeze half a lime over the salmon. Drizzle with 1 tablespoon olive oil and let sit for 3 minutes before serving. Serve as an appetizer, with thinly sliced, dense homemade bread or toasted white bread. RAMEQUINS D'AVOCAT AUX COQUILLES ST. JACQUES (Ramekins of Avocado with Sea Scallops) (4 servings)

While reminiscent of guacamole and seviche, this is a very rich, delicate and suave version of avocado puree and raw marinated scallops. And being such a rich appetizer, it could easily serve twice as many people as Leyerle recommends. For the avocado mousse: 2 avocados Juice of 1/2 lemon 1/2 cup whipping cream Salt and pepper to taste For the scallops: 1 1/2 pounds sea scallops Juice of 1 lemon or 1 lime Salt to taste Hot pepper sauce to taste 10 tablespoons olive oil 1 tablespoon mixed fresh herbs (parsley, purslane, chives, for example)

Scoop flesh of the avocados into a food processor, along with juice of 1/2 lemon, whipping cream and salt and pepper to taste. Process until smooth and fill four small ramekins with the pure'e. Refrigerate for 2 hours or more.

In the meantime, prepare the scallops. Combine scallops with juice of 1 lemon or lime, salt and hot pepper sauce to taste and olive oil. Add fresh herbs, in whatever combination you like, to total 1 tablespoon. Set aside for 1 hour.

When ready to serve, unmold avocado mousse onto cold plates. If it does not unmold easily, scoop it onto plates. Remove scallops from marinade and set marinade aside. Slice each scallop in half to make two thin rounds. Return to marinade, toss well and let sit for one minute, then arrange scallops like the petals of a water lily around the avocado mousse. AIGUILLETTES DE CANARD AUX CHAMPIGNONS DU CAPITAL ET PETITS OIGNONS NOUVEAUX (Sliced Breast of Duck with Mushrooms and Scallions) (4 servings)

This dish was invented and named following a dinner party at which Leyerle was served mushrooms unlike any he had seen before. What were they and where were they from? From the front yards of Capitol Hill, he was told, and was taken to see them in their natural habitat. Fearing for his life, Leyerle was relieved to wake up healthy the next morning, and celebrated with christening this dish. He recommends, despite its name, buying shiitake mushrooms, available at Hudson Brothers in Georgetown, or if necessary, making it with ordinary cultivated mushrooms, but certainly not picking unknown mushrooms. For the duck: Boned breasts from 2 ducks (skinned if preferred) 3 tablespoons butter 1 tablespoon peanut oil Salt and pepper to taste 3 tablespoon bouillon or duck stock 1 pound fresh shiitake or other mushrooms, quartered 2 bunches scallions, cut into 2-inch lengths Sauce: 1 tablespoon butter 2 shallots, minced 1 cup red wine 1/2 cup duck stock, made from bones of ducks

Heat 1 tablespoon of the butter and 1 tablespoon oil in a saute pan large enough to hold the duck breasts, and saute' them over high heat for 2 or 3 minutes, just long enough to leave the center of the meat rosy. Season with salt and pepper as they cook. Remove from pan and set aside to keep warm.

Heat remaining 2 tablespoons butter and 3 tablespoons bouillon or duck stock in another saute' pan over high heat. Cook mushrooms and scallions in it, shaking the pan, for about 8 minutes until the liquid boils away and the vegetables glaze. Remove from heat immediately or the mushrooms may begin to exude juices.

To make the sauce, heat 1 tablespoon butter in a small pan. Saute' shallots a minute or so until softened. Deglaze the pan with red wine and boil until reduced to 1/2 cup. Add duck stock. Season lightly with salt and pepper to taste and simmer 15 minutes. Adjust seasoning.

Cut duck into long, thin slices. Cover with sauce and garnish with the mushrooms and scallions.