OISHI is popular, very popular. A recent Sunday evening, often a slow night for restaurants, was standing room only. Unfailingly calm and considerate, the front desk staff seated people quickly despite the crush of couples and families at the door. Nearly all of the 30 or so tables in the main dining area were occupied, as were the 10 or 12 seats at the spare, elegant sushi bar at the back of the room. Three sushi chefs, dressed in white, worked with the concentration and deliberate speed of surgeons in an OR. Only one of the four hibachi tables — in a separate room but visible through large glass windows — was operating, apparently because of some technical glitch with the equipment. The atmosphere in the main dining area was urbane, quite different from the mall environment on the outskirts of Newtown, Pa., where the restaurant is located.

   Tables-for-two were available, so we were seated immediately. Larger groups had to wait, but “no more than 15 minutes” promised the cool-headed maitre d’. Our server appeared almost immediately, greeted us pleasantly, opened our wine, provided an ice bucket on request, and despite the crowd gave no hint that the staff was working under pressure. She took all the time we needed to understand the menu.

   The crowd was there for a reason. Oishi offers well-prepared Japanese cuisine, supplemented by Thai and Korean dishes, with some sophisticated fusion dishes difficult to characterize by national origin. With all that variety, it’s no surprise that the menu is long. It begins with a half dozen soups, ranging from the familiar miso to the more exotic Korean dumpling, with beef dumplings, scallions and egg, along with cellophane noodles. Eight salads are available and a wide range of appetizers drawn from a variety of Asian cuisines. Among them are Oishi pancakes — wheat flour and mung bean — that come with the diner’s choice of seafood or vegetables or kimchi, Korea’s national dish of pickled cabbage and white radish with chili, garlic and ginger. Also available are Thailand’s chicken satay with its peanut sauce and Japan’s yakitori, skewers of chicken with teriyaki glaze.

   We began with two of the Thai soups. The hot and sour lemon grass soup ($4) had a base of limejuice as a bath for baby shrimp that were big babies. It was piquant with a spicy kick. The coconut chicken soup ($4) was sweet, yet light, with the rich coconut milk offset by the tart lime juice, lemongrass and cilantro. The chunks of chicken were tender. A starter from the sushi side of the menu supplemented the soups but only after a pause of about 10 minutes. Despite their obvious dedication to their tasks, the sushi chefs were backed up, and apparently there was some confusion over the order — our server returned to verify that we had ordered the tuna tadaki not the tuna tartare (which eventually showed up on our bill). The tadaki ($12) is thin-sliced, seared yellow tail served with ponzu sauce (soy sauce fortified with citrus juice), and that is what we had ordered. The flash-seared tuna was sliced to a sixteenth of an inch, but lacked the peppery coating that usually enlivens this dish.

   Entrées represent all three Asian cuisines, and we barely skimmed the surface of the extensive variety of dishes available. Entrées from the grill include rice dishes such as Japanese or Thai curries, tempura, noodle dishes, and three pages of sushi and sashimi selections, available by the piece or in set menus that range in price from $18 to $65 and in size from eight to 30 pieces.

   We chose from the grill options and the sushi. Grill entrées are accompanied by complimentary miso soup or salad, which we skipped. Diners can choose Japanese teriyaki (steak, chicken, salmon, shrimp, red snapper or tofu and vegetable) served over grilled asparagus; Korean bulogi (thin sliced cuts of marinated beef or chicken grilled over an open flame); or the Thai-inspired royal oishi ($19), which was our choice. But we still had to select among several options. Would it be salmon, red snapper, or shrimp and scallops? We chose the red snapper, which was served with coconut lime sauce, grilled bok choy, asparagus and zucchini. It delighted the eye and the tastebuds: the fish was tender and moist, the coconut lime sauce subtle and intriguing, and the vegetables gently grilled to retain their crispness. The dish was a triumph of fusion.

   Less successful were our sushi choices. The Screaming Spicy II roll ($6) — fresh salmon, cucumber, crabmeat, avocado and a spicy sauce — didn’t come close to spicy, much less screaming spicy. The chef’s spice-o-meter was set too low, and the cool salmon, cucumber, crabmeat and smooth avocado moderated any hint of spice. The dragon roll ($13) included grilled eel, avocado and caviar accompanied by eel sauce. The eel had its characteristic smoky overtones, but the consistency, ideally lush and buttery, was simply too soft.

   Desserts number only four, of which the most notable are homemade coconut ice cream ($4) and Japanese mochi, sweet rice cakes filled with strawberry, mango or chocolate ice cream ($5). In the only slip in the evening’s otherwise dexterous service, our server presented the bill without offering tea or dessert. Then, as an afterthought, she asked whether we’d like dessert. We were satisfied, and it wasn’t necessary — but those mochi, and other enticements such as the Korean specialties, may call us back to Oishi.