-- 1736 L St. NW. 331-9771. Open: for lunch Monday through Friday 11:30 a.m. to 2:30 p.m., for dinner Monday through Thursday 6 to 10 p.m., Friday and Saturday 6 to 10:30 p.m. Closed Sunday. AE, MC, V. Reservations suggested. No separate non-smoking section. Complimentary valet parking at dinner. Prices: lunch appetizers $5.50 to $10, entrees $12 to $19; dinner appetizers $6 to $14, entrees $12 to $26. Full dinner with wine, tax and tip about $55 to $65 per person.

How much would you be willing to spend for great bread? Thirty dollars to $60 per person? Then make a reservation at Twenty- One Federal. There are other compelling reasons to dine at Twenty-One Federal, but the bread alone is worth it -- two or three kinds in the basket, the variety changing at each meal. You can hope for the dark, anise-scented pumpernickel with its moist chewy crumb and heavy crunchy crust, or the little squares of corn bread so uniquely rich and fine-textured that they must be made with heavy cream. And sometimes there are slices of multi-grain bread with a fibrous crunch on the inside and a crust studded with sunflower seeds, or a cranberry bread nearly as creamy as the corn bread. With the breads come slabs of fresh sweet butter. Together, they would be the makings of a memorable meal.

But at Twenty-One Federal, they are just the beginning.

Twenty-One Federal is a branch of a Nantucket restaurant of the same name, and much of the staff, in addition to chef Bob Kinkead, has emigrated for this project. Maybe that's why it has a certain New England steadiness to it.

The dining room is light and modern yet solid and luxurious. In front is a lounge with a black-and-white marble tile floor and high-tech black bar stools, separated from the dining room by a floor-to-ceiling glass-walled wine vault. Though the dining room soars and its walls are covered in exotic blond wood by the acre, it manages to be intimate, its floors of marble mosaic alternating with wood to create the illusion of separate rooms. The decorations are simple -- strips of marble mosaic inlaid along the walls -- and luxurious, with immense bouquets of flowers on pedestals and sideboards. Twenty-One Federal looks like a contemporary art deco interpretation of a grand old Boston dining room.

The waiters and waitresses are as polished as the dining room. Rarely does a new restaurant start with such calm and expert service. The kitchen can be slow, but the dining room is alert.

Even with such a handsome dining room and suave staff, the food is the star at Twenty-One Federal. This is new American cooking at its best, with its emphasis on extraordinary fresh ingredients and a grounding in tradition. Chef Kinkead first of all deserves credit for finding suppliers of such fresh young greens, such plump mussels, such pristine smoked fish, such outstanding pork.

Next, he presents food that is at the same time simple and complex. Each ingredient is left to show its natural assets, but the combinations are intricate. A salad of roast pork, grilled eggplant, tomato, fried okra and cilantro mates slices of tender pale pork with an intense thick southwestern-style sauce and a thinned variation of herbed mayonnaise.

Or consider the swordfish carpaccio, one of the most delicious appetizers I have tried in months. The swordfish itself is thin, raw slices spread on the plate so their translucence is just a shimmer under the garnish -- which is shaved raw fennel, toasted pine nuts, raisins, minced fresh herbs and a border ruffle of arugula. Again, each component is identifiable, yet all meld into an extraordinary contrast of textures and flavors as well as colors.

One caveat here: Appetizers and desserts are consistently more outstanding than main dishes at Twenty- One Federal. For example, the lobster- and-crab cakes are available as appetizers at both lunch and dinner, and they are not to be missed. They are lightly bound and highly seasoned in a southwestern mode, accompanied by a relish of corn and okra and a cream sauce spiked with mustard. Mussels, available at lunch, are also seasoned with mustard and cream. Also on the lunch menu is a charming -- and very good -- plate of raclette, the melted cheese accompanied by slices of grilled potato, marinated red onions, pickled white onions, gherkins and two kinds of mustard. And there is a very rich lobster and corn chowder that is generous with its lobster.

The dinner list includes delicious oysters wrapped in pancetta and grilled so that the bacon is crisp but the oysters are juicy; their powerful sweet-sour vinegared brown sauce knifes through the richness. A southwestern seafood soup called zarzuela is both pungent and delicate and shows off this chef's New England instinct for cooking seafood. He also arranges several kinds of smoked seafood beautifully with tiny dabs of three caviars on a palette of sieved egg whites and yolks, minced shallots, cracked pepper, strands of chive and an edible flower leaf on horseradish cream.

Main dishes are generally good. Swordfish is cooked perfectly and aptly moistened with a vinaigrette of tomato and grilled scallions. Duck breast in a light and faintly sweet port sauce with a julienne of crisped Smithfield ham and tangerine wedges was just fine. And lobster ravioli not only looked glorious in a pool of herb-studded and pistachio-tinged cream sauce with big chunks of lobster, but it was a mellow and satisfying dish. Spit-roasted chicken was timed well and agreeably seasoned with lemon, garlic and fresh herbs. Sweetbreads caramelized to a golden brown yet moist and tender inside, accompanied by caramelized shallots, were a tour de force. At lunch, a pot pie of turkey, chicken and duck was rich, hearty and quite luxurious, cleverly topped with a large round of crust reminiscent of a pilot cracker. And spit-roasted lamb, cut in long, thin, pink slices on a highly reduced dark brown sauce, was plain good food, enhanced by an endive gratin. All these dishes ranged from pleasant to excellent, but they didn't have the impact of the appetizers. Then there was a "lasagna" of sweetbreads and wild mushrooms that tasted overwhelmingly of ricotta and not of much else, and a grilled sushi tuna that should have been left raw inside to live up to its name.

Presentations are glorious, with bits of potato pure'e or, in the case of the tuna, wasabi piped into rosettes, and delicious morsels of vegetables, often buttery spinach leaves. Everything is cut and arranged with precision but without looking tortured. Snipped fresh herbs and whole sprigs of herbs perfume the plate, tiny dices of tomato add color to a creamy sauce. This is stunning food, but the garnishes all add their own taste as well as color and shape.

While the wine list is not one of the city's longest, it seems one of the most carefully chosen and best priced. There are good bordeaux and burgundies for just over $20, excellent California choices in the same range and a few Italian wines.

Considering the breads, the desserts could be expected to be special. And they are. The bread and butter pudding with bourbon pecan sauce is nearer a cre`me brule'e with bits of brioche and topped by a boozy custard sauce, a ribbon of whipped cream and sugared pecans. The warm apple crisp is very tart, perhaps too sharp on its own but perfect with its heavily spiced cinnamon ice cream. Chocolate stars in desserts of several different styles and textures. Specials might include light little puff-pastry turnovers stuffed with homemade quince and raspberry preserves.

Unfortunately for Twenty-One Federal, Washington's dieting habits may keep many venturers from finding its best parts. This is not a restaurant where you should eat lightly, skip the appetizer and forgo the bread. The main courses are its weak point, but even so this is a strong addition to the top ranks of Washington's restaurants. ::