Anchoring a downtown corner under a bright neon sign, La Esquina looks like nothing more than a fast-food taquería, with cheap tacos sold to-go until 2 in the morning. Just around the corner, though, is a modestly priced café serving those same tacos along with more ambitious fare like chiles rellenos (stuffed peppers) and carne asada (grilled meat). The real draw, however, is hidden from sight: the basement brasserie, like a Mexican speakeasy, is accessible by reservation only, through an unmarked door just inside the ground-floor taquería. Inside, discover a buzzy subterranean scene with pretty people drinking potent margaritas and dining on upscale Mexican fare. Prices downstairs are high, but portions are large.