Open for lunch Monday through Friday 11:45 a.m. to 1:30 p.m.; for dinner 6:45 p.m. to 9:30 p.m. Monday through Saturday; for after-theater desserts and champagnes 9:30 p.m. to midnight Monday through Saturday. AE, CB, Choice, DC, MC, V. Reservations. Valet parking $6, self-parking $3, for lunch and dinner. Prices: Three- and four course lunches $22 and $28, respectively; five- and six-course dinners $50 and $68, respectively. Also ,a la carte, appetizers and main courses $10 to $16. Full dinner with wine, tax and tip $80 or more per person.

Washington's people-watchers may turn into plate-watchers as soon as it is discovered that from a particular spot on L Street you can look up through the windows of Le Pavillon to see two tables reflected in the mirrored ceiling. What they show is that Yannick Cam is back in the kitchen creating plates that are more beautiful than ever.

His new restaurant, moved from a K Street basement to the mezzanine of a glass office tower, is now decorated to the taste of Cam and his wife-hostess, Janet. It is the setting they deem worthy of his food: Limoges china, heavy French silver and jewel-cut crystal. The backdrop is luxurious, with velvet and silk in pale peach, smoke and greige, and the three rooms--small yet spacious for the number of tables-- are like an art gallery, more to enhance than to be noticed themselves.

The exhibition is the food, and it changes twice daily. At dinner there are two fixed-price menus: five courses at $50, six courses at $68. Lunch has two menus: three courses at $22 and four courses at $28, but the choices are wider than at dinner. Anyone who expects to eat fewer courses by ordering ,a la carte had better reconsider, for these are portions are not full-size Western servings.

A few dishes and most of the desserts appear regularly on the menu, but the majority change daily. For the time being you might find brandade of sole with lobster coral and caviar, served in an eggshell--with gorgeous silver egg cups. It is good, but not one of the chef's best. You loved the filet of beef with basil sauce? The next time it will be with red wine sauce. The new American foie gras is usually available as a tiny mousselike gateau, though one day its garnish might be confit of onions, another day a caramelized fig half. Sage and mustard butter sauce,s extraordinary here, is on the veal today, but it will show up on the pigeon tomorrow.

One doesn't dine at Le Pavillon with one's mouth set for a particular dish, but with a general expectataion of a delicate meal of constant surprises. So there is less sense in recommending particular dishes than in describing Cam's style, which is more developed, more original and more mature than ever. Cam uses ingredients in new dimensions, but never slips into the bizarre or dissonant. Bits of broccoli--matelote aux brocolis--are scattered over airy slices of pale pink crayfish mousse. Tiny dices of wild mushroom are crusty bursts of flavor to contrast with saut,eed cubes of salmon. Two lone sprigs of fried parsley play against the tiniest cubes of unctuous eggplant to transform most subtly a medallion of lamb.

These dishes are meant to be eaten in a succession to form a medley. Some of the portions are tiny--three slices of fish on a warm salad might combine to the size of a matchbook--and others are unexpectedly large (well, normal)--two conventional-size quenelles as an appetizer, a substantial salmon fillet and a lunch main course. Frankly, some of the portion sizes are simply too small: the three vegetable pur,ees with duck or pigeon are mere dabs, and a luscious turnip gratin allowed only two pitiful nibbles. It is an argument that will continue: Cam and his disciples favor such portions as aesthetically satisfying and presenting no danger of overstuffing the patron. Others would prefer Cam leave it to the patron to decide. And although by the end of dessert one generally feels securely well-fed, that is not apparent from the beginning.

Whatever the size and the wait (and whatever the cost) the food is exciting. Here is a warm salad of rouget meltingly soft, on tiny pourpier leaves with mellowed confit of leeks and little slices of truffle in nut oil. Langoustine are served in a soup bowl (though one day looking more like the leavings than a whole portion) in a cream perfumed with truffles and with the bite of julienned endive, or with quail eggs and pur,eed onions. Crab is baked in a cloud of custard and sauced with pur,eed corn and mushrooms. And the meat courses are stunning, whether ruby red and crusty slices of beef garnished with a tiny roulade of red pepper, lobster mousse and coriander leaves arranged like a flower, or superb marinated pigeon, its rare slices napped with that haunting sage and mustard butter sauce. Oh, there are flaws: One evening two portions of gateau d'ecrivisses were quite different, one delicious and velvety, the other salty and rubbery. One crab flan was thin and firm, the other tall and fragile. While the fish is typically cooked as if by some magical velvetizing process, it has twice been cooked a disappointing few moments beyond suppleness.

The wine list creates excitement. That so many '59s and '66s and '70s should be available at prices possible to consider, that a fine French champagne can be had for $24--and for $12 a half-bottle--and that one can drink a wine worthy of Cam's food from $25 are endearing traits of this restaurant.

Desserts are even more delicious than one remembers from the earlier Pavillon. The bitter chocolate terrine with hazelnut meringues is richer and lighter. The white chocolate mousse doesn't pall after years of tasting it, andthe large cookie with lemon curddand strawberry sauce is now excellent where it once was only fair. Beautiful miniature raspberry tarts float on a marvelous apricot sauce traced with raspberry, but their pastry can be tough or soggy; better are the fruit bavarians-- mango or white peach--that distill summer on the plate.

The restaurant improves each week. The waiters need to lighten their otherwise smooth demeanor and keep a more constant eye on their tables. And one hopes the kitchen will get its rhythm--and speed its pace when necessary--expand the menu, offer a cheese course--Cam says he will--and present little after-dinner sweets that other restaurants of its ambition automatically serve.

One cannot expect a restaurant so new to bring in a perfect report. In fact, I would hope it would not. After all, with a restaurant this exciting, I welcome an excuse to look in on it again before long.