Part of the minichain (or Ho Chi Minh-i chain) that includes Ahn, Cyclo and Nam, O Mai pulls in a stylish Chelsea crowd with its snappy spin on Southeast Asian cuisine. The spicy beef salad combines tender meat with lemongrass, peanuts and vegetables; mint-accented monkfish, served on a sesame rice cracker, has a mild, earthy flavor. Entrées can be disappointing; the chili-lime sauce on the panfried snapper lacked kick, and a side of lemongrass tofu was a bit scorched. Still, cool design and warm service keep this a date-worthy destination.