This Upper East Side townhouse recalls the civilized yet exotic world of French Indochina, with black-and-white period photos, ceiling fans and lush potted palms that convey the beauty, romance and spirit of another place and time. The main dining room provides a formal setting for lunches and dinners of savory, authentic Vietnamese cuisine, while the second-floor lounge and bar provide a more casual setting for groups or an intimate rendezvous.