Sushi Azabu at Greenwich Grill 
428 Greenwich St., 212-274-0428, TriBeCa, Manhattan
Greenwich Grill looks like a handsome, garden-variety TriBeCa establishment, but there's another restaurant hidden within it. Head for the waiter station, swish through a black curtain and descend the stairs to a secret sushi den where reservations are required a week or two in advance. The capacity of the Michelin-starred Azabu is just 22, with three round booths for groups and four seats at the bar providing a front-row view of Japanese artists who have super-sharp knife skills. Impeccable sourcing of seafood, much of it from Japan, is key, and the menu changes depending on availability. The room is so quiet, tasteful and authentic, it's like beaming into Tokyo for a night. Everything is available à la carte, and there are also tasting menus starting at $35. The chef's omakase extravaganza starts at $100.