As restaurant neighborhoods go, the East Village is the equivalent of a Honduran tilapia farm: packed to the gills and in danger of polluting the ecosystem (in this case, with middling restaurants). But Pata Negra, sandwiched into a narrow space on 12th Street between the takeout and proper restaurant locations of mac-and-cheese stalwart S'MAC, has proven itself as a sleeper in the tradition of Spain's best tapas bars, and the area is better for it. Wallets and waistlines, not so much. More