Sushi has become such a fixture on the American dining scene that stepping into Nobu's feels like traveling in a time machine — and not just because it's located in an old IHOP. (The unexpected setting does help, though.) The location, the serene atmosphere and the preternatural elegance with which Noboru Kidera arranges a piece of nigiri sushi: together, they evoke a time when sushi wasn't one more lunch-hour option or fast-casual trend but an actual mystery. Is this dinner? Or is it art? Neither. This, like all great sushi, is a revelation. Only when you try luscious toro can you really understand the flavor of tuna. You may never order baked or grilled salmon again after you've sampled Kidera's simple, exhilarating pairing of raw salmon with raw onion. And if all you know of sushi is American-style rolls — well, you may find a few of them here, but you should really try the traditional futomaki rolls. Each bite is like a burst of ripe summer fruit, and you get six revelations to an order.