In his sleek, modern dining room, Ryan McCaskey revels in subtle flavors gorgeously arrayed on the plate. Aided by pipette and tweezers, the Saigon-born chef creates sophisticated magic with sumptuous touches, such as caviar, truffles, and marrow, that harmonize with fine seafood and meats in delicate saucings. Supporting vegetables appear in unexpected ways: celery-onion cream on Montauk oysters, caramelized rutabagas with flank steak. Some surprising lapses in hospitality offset all the wonderfulness, however, ranging from slow service to skimpy wine pours and a resistance to substitutions. Five- and 10-course tasting menus vary seasonally. Inventive cocktails and serious wine program.