Open for dinner Monday through Saturday, 6:30 to 9:30 p.m. All major credit cards. Reservations recommended. Parking garage in building. Prices: Fixed-price dinner $25 ($30 with house wine) and $40. A few a la carte items $15 to $25

I wouldn't go so far as to suggest that it is your patriotic duty to dine at Jean-Louis, but Jean-Louis Palladin, one of the most talented chefs ever pried from a kitchen in France to cross the seas, is cooking in Washington and talking about leaving. And if Washington loses him through any fault of our own, we deserve a seven-day diet of mealy frozen Dover sole smothered in onions.

In the restaurant named after him, Jean-Louis is inventing and serving the 1980's version of nouvelle cuisine (which chefs these days prefer to call free cuisine) using all American ingredients. His establishment and Le Pavillon are the city's only nonclassical French restaurants injecting nouvelle excitement into local dining. Although the two are a complement rather than contest in this city, Jean Louis has the obvious advantage of a small elegant dining room decorated in a startling manner with cloth shingles on the walls and accented by a very few but beautiful paintings and flower arrangements. It is an orange cave with mirror tricks turning the curving walls into more unorthodox shapes, reflecting a corner of garden on the ceiling, and showing you -- disconcertingly -- unexpected glimpses of yourself. Heavy white damask covers the large tables, which are set with flowers -- orchids, violets and the like -- floating in glass globes, and handsome floral service plates; phalanxes of weighty silverware include fish knives and sauce spoons. The music and carpeting are deep and soft. Like the food, the dining room is experimental, extravagant yet spare, and intriguing if not successful in each detail.

One Friday evening's dinner started with canapes of homesmoked goose breast, salty and supple dark red meat. We drank with it tall flutes of champagne tinged pink and fruity with raspberry liqueur. Then a companion and I tried one $40 tasting dinner of six subsequent courses and one of the two $25 three-course dinners. We bypassed the few exorbitant a la carte choices like leeks with truffles, lobster with beans and rack of rabbit with Japanese mushrooms.

First comes an immediate fanfare, great slabs of homemade brioche, brioche so tender and buttery and light as to be the best brioche in anyone's recent memory, according to an extensive survey I conducted. With it comes whipped anchovy butter, the first hint of unexpected juxtapositions that will be teasing the palate through the evening.

After one has been stirred to applaud the bread, the next of the meal's highlights comes, for the fish courses are Jean-Louis's finest compositions. That Friday the soup was a dark, full consomme floating tender, barely cooked lobster medallions and Maine's belon oysters wrapped in lettuce leaves and set adrift to let the broth warm them. A similar soup I tasted a month before had been far too salty, and a friend dining later than evening found the soup again too salty.

Over-saltiness is a problem that plagues newly-arrived French chefs who are used to European coarse salt, but it seems to be under increasing control here. Some earlier visits to Jean-Louis produced watery minced shrimp and flown-in foie gras under sundae sauce, pasty purees and main course sauces memorable only for their saltiness. By February the culinary problems seemed largely resolved, and Palladin had begun to invent new roles for American raw materials.

It was just the beginning of shad season, and he had discovered a new personality for shad and its roe in the disguise of "blanquette of fish with fresh mint." Small batons of shad were poached -- just barely -- and arranged as spokes interspersed with slices of roe that were so soft and creamy as to be mistaken for sea urchin. Even the shreds of vegetable -- celery, carrots, leek and probably turnip -- took on new dimensions, cooked to a crisp sweetness that contrasted with the delicate fish and the pale sauce seasoned with mint so lightly that it was an undercurrent rather than a dominating flavor. Pompano in watercress sauce, too, was thinly sliced and poached to a supple texture, sauced with a light green subtle cream and garnished with just-blanched watercress leaves so that cooked and raw interplayed.

Palladin sauces rabbit with ginger, duck with lime, scallops with broccoli or tangerine, kidneys with nectarines, sweetbreads with mint. But never do those unexpected flavors dominate; you would be hard pressed to identify the presence of the ginger or the nectarine puree, for they are catalysts and balancers rather than main themes.

In the nouvelle cuisine style, sauces are light-textured, thickened primarily with vegetable purees if at all, intense with meat and fish reductions, more likely to be heavy in flavor than in texture. Their richness in flavor is balanced by restraint in butter and cream richness. Unlike many nouvelle cuisine practitioners, Jean-Louis does not overload his menu with cream sauces. He does, however, succumb to sweet accents in too many of his brown sauces. Duck with lime eclipses the bite of lime with too much sugar. Lamb with peaches is nearly superlative, its thick lamb filets crusty and rare, the peaches lightly cooked in a way that intensifies their perfume.The dark, glossy sauce, faultless in its texture, is definitely sweet, too much so for my taste.

The genius of this new cuisine, however, is highlighting essential flavors and thereby creating surprises, much as closeup photographs of familiar objects become strangely beautiful and unidentifiable. Slivers of the peeled stems of nearly raw asparagus taste as sweet as fruit. Paper-thin rounds of mushroom in a blanquette de veau -- an extraordinary blanquette de veau -- are soft and earthy and nearly sweet. Peaches taste more fragrant than ever. Broccoli cream sauce has the kind of flavor you know you recognize but cannot place. Even when dishes don't quite work, such as mushrooms turned into a dessert compote, they are teasing to the senses and exhilarating. And the fact that these compositions are created with everyday American ingredients rather than flown-in exotica is particularly exciting. Wait until Jean-Louis Palladin discovers just-picked Silver Queen corn and mulberries and softshell crabs!

Also in the nouvelle cuisine style, portions are small at Jean-Louis, and in the early days one diner complained, "We didn't know when we had the main course." That has seemed less of a problem lately. There are, however, problems still to be tackled. While the restaurant is to be commended for being one of the few luxury establishments to employ women in the dining room, the waitresses lack experience and are still awkward. And their uniforms look more like housedresses than formal wear. Drinks and wines have been served too slowly, though the kitchen has paced food service well. And some patrons have been offered an incomplete choice of desserts, thus missed the best. Dessert can be glorious at Jean-Louis, but a few of them, particularly the meringues, are dull and oversweetened. Lime or lemon tart, on the other hand, is the creamiest, tangiest sensation in a bare crunch of a crust. Rhubarb tart is similarly fragile and tangy and refreshing. Every pastry, from the Paris-Brest to the mille-feuilles, is luscious. Chocolate mousse is dense and wonderfully bittersweet, and the passion fruit sherbet available one day, though a breathtaking $8 a portion, was stunning in flavor, impeccable in texture.

It will probably take time for Jean-Louis to overcome the flaws in some American ingredients. Our ducks can be tough when cooked rare, so sliced duck breast has been a disappointment. And the duck livers are strong, overpowering in otherwise fascinating sliced chicken legs stuffed with duck liver and laced with truffles and brown sauce. Very good chicken livers would have melded better. Our cheeses -- or at least the cheeses Jean-Louis has been receiving -- can be bland and underripened.

Still, dinner at Jean-Louis can be the most exciting in town. Even a simple green salad with hazelnut oil brings a new appreciation to spring greens.

While one can easily spend $150 a couple for dinner, the fixed-price meal with house wine can cost half that including tax and tip. The problem with restraining the expense, though, is not that one will eat less grandly, but that the wines will be an insult to the food. The restaurant imports its own red and white house wines from France, and while the white is acceptable, the red is insipid. Further, the glass-fronted wine cellar, though filled with legendary bottles, is populated with outrageous prices. Each day a small wine list of the day is printed on the menu, and one is hard-pressed to find a wine at a less-than-irritating price. On my latest visits, the least expensive wines on the menu nudged $20, and even the choice at $30 a bottle was not enticing. A fuller listing of the cellar, said to be in preparation, will be welcome.

Dinner ends with very good coffee brewed to order in a Melior pot and served in lovely Chinese red cups. It sums up the little attentions, the luxury of detail that the restaurant encompasses.

Jean-Louis is the kind of restaurant that I was inclined to recommend to people who called asking for a restaurant appropriate to marriage proposals. In fact, I did so twice, and it apparently served the purpose well. I avoided recommending it to a third only because he wanted a restaurant that could be expected to be around for his 10th anniversary.

For that, all we can do is hope.