HILL CAFE -- 332 Pennsylvania Ave. SE. 547-8668. Open: for lunch daily 11 a.m. to 3 p.m.; for dinner Monday through Thursday 5 to 10 p.m., Friday and Saturday 5 to 11 p.m., closed Sunday. AE, MC, V. Reservations suggested on weekends. Separate non-smoking section. Prices: lunch appetizers $2.50 to $4.50, entrees $4.95 to $7.50; dinner appetizers $5.50 to $8, entrees $10 to $20. Full dinner with wine or beer, tax and tip about $35 to $40 per person.

Two restaurants don't necessarily make a trend, but they certainly reinforce a good idea, in this case Japanese-French cooking. The first was Cafe' Japone, which is to be praised more for its Japanese cuisine than for its hybrid cooking. And now Hill Cafe' has opened on Capitol Hill, serving far more adventurous and complex Japanese-French dishes at dinner (along with sushi) and western sandwiches with a few eastern touches (and a few Japanese standards) at lunch.

Hill Cafe', the second venture to spin off from Yosaku and Perry's, has been open for months, but it keeps playing around with its concept, so the menu has been quite different on each of my four visits. Thus, while the menu seems to have stabilized, don't be surprised if it changes before you give it a try.

What has been established from the beginning is that this is one of the most attractive restaurants on the Hill. A flashy set of rooms is decorated with modernized Japanese themes. Set in relief on the walls are folding screens and columns, lacquered collages in deep jewel colors of rust and burnt orange with splashes of gold. Tables are splashes of more gold against black in an oriental version of Jackson Pollock-style spatters, and sushi trays are painted to match.

The lunch and dinner menus are totally different, and the sushi bar is open only at dinner. Lunch is only minimally Japanese, but it greatly expands the Hill's narrow options. Tempura, chicken teriyaki and a sushi platter are on the lunch menu, and at $6 to $7 they might be considered bargains. The teriyaki has been the best of these lunchtime entrees, its meat juicy and its surface well browned. Tempura was mundane -- a bit heavy in the batter -- and the sushi lunch was a disappointment, just a few pieces of maki and California roll; the only fish on it was crab-shaped surimi. A Japanese seafood salad mixes East and West, and the pretty result is a tangle of various seaweeds, a couple of butterflied, supple and sweetly marinated shrimp, some sliced raw scallops and pale raw fish slices formed into a rose with a topping of bright red roe. The salad's several dressings and marinades, based on sweet vinegars, swirl their colors and fragrances to lovely effect. Another international mix is chicken and shiitake mushroom consomme', a pleasant soup flavored mostly by the mushrooms and soy sauce.

Several months ago, the lunch specials included combination plates and a too-sweet but otherwise delicious sukiyaki platter; on the current menu, I would stick to the occidental sandwiches. These venture into combinations of roast beef with watercress and shiitakes in wasabi mayonnaise, a chicken club with avocado dressing, turkey with chopped liver on a croissant, tuna with fresh dill, blackened flank steak on snow peas with roquefort and my favorite, called the Little Italy. Its hollowed-out Italian roll is heated to a crunch and stuffed with tomato-onion sauce, saute'ed spinach, layers of prosciutto and strips of saute'ed eggplant lacquered with melted smoked mozzarella. It may not be Japanese, but it is inspired.

At dinner the chef creates fantasies on the plate, though their fulfillment is sometimes vague. Appetizers are dreamy-looking creations -- with pink, green and saffron-yellow sauces, dollops of caviar in several hues garnishing scallop mousse or raw scallops teamed with a bed of lentils and snow peas in a western vinaigrette. Chicken mousse is wrapped in napa cabbage pyramids and steamed. Giant clams are sliced and stuffed with crab meat and tarragon butter, and tiny eel-like shirauo fish are tossed with endive cut to their shape and floated in a pink beurre blanc etched with white. In all, the sauces are forthright and colorful, the combinations of flavors intriguing.

Less adventurous are the sushi and sashimi, but even there you might find surprises, perhaps raw sweet shrimp or bonito as daily specials. The quality of the fish is on a par with most sushi bars in town, but the sushi chef is at his best when he adds a band of seaweed here and another garnish there to special effect. The list of sushi rolls ventures into pretty red tuna with starchy white yamaimo, and even rolls with turkey and shad roe or ham and cheese.

Main dishes seem more French and less Japanese, and the richness of the sauces is sometimes overwhelming in these larger portions. The most memorable main dish was steamed rainbow trout with crab meat and red pepper beurre blanc, though the trout seemed more like sea trout than rainbow trout to me. It tasted utterly fresh and moist, with a delicate contrast of scallop mousse and crab and a subtle pepper sauce. Shrimp Moulin Rouge also was pleasant, the shrimp wrapped a little awkwardly in sole fillets, on a yin-yang design of red and yellow sauces. Slices of duck, coarse and tough, were in a good old-fashioned flour-based brown sauce with green peppercorns. Much more interesting were its accompaniments of lentils tossed with crisp bits of duck skin and golden brown potato au gratin. Steamed fish and abalone sounded oriental but tasted dull, with chewy abalone and bland fish sunk into a very rich sauce. Like the duck, its accompanying vegetables -- tiny balls of zucchini and carrot -- were better than their main theme. The veal loin was a more refined meat than the duck, and was cooked impeccably, but its glossy brown shiitake mushroom sauce was excessively salty. It added up to merely decent French food.

The menu also lists red snapper meunie`re, saute'ed salmon, and lobster with American sauce. On the meat side there is roast chicken and a couple of standard French steak preparations. In all, I would concentrate on appetizers and sushi. The main dishes, particularly the meat dishes, are more like French dishes cooked by a foreigner than adaptations of French food by an artistic Japanese sensibility. They look pretty and unusual but taste slightly amateurish, lacking a professional finish. French cooking is done better elsewhere on Capitol Hill, though the prices at Hill Cafe' are reasonable enough for there to be some flaws.

Desserts are glamorous-looking concoctions of cake layered with strawberries, kiwis or glossy chocolate, set on a composition of painted sauces and caged in a fluff of spun sugar. None of them tasted nearly as impressive as it looked, though a poached pear stuffed with chocolate mousse and coated with chocolate sauce under a spun-sugar halo was a dazzling combination.

Service reflects the food. It is eager and ambitious. Waiters try so hard that you want to set them at their ease and will them to relax. In their anxiety they have brought the wrong dishes, hovered at the table and generally transmitted their nervousness. Even when only a few tables have been occupied, the kitchen has been excruciatingly slow. It will have to pick up the pace considerably to be in tune with the mad dash of Capitol Hill lunchtime.

Hill Cafe' may yet turn out to be the best culinary news on the Hill in years. It is a beauty, and the menu is full of imaginative surprises. Much of the cooking, though, tastes experimental and unpolished. Practice may take it closer to perfect, but in the meantime, proceed cautiously and be ready to retreat to good sushi or a great sandwich. ::