Chef David Guempel's Zinnia is a sweet spot in an improbable locale: a former gas station on Big Bend, just north of Laclede Station Road. The place is painted an unlikely color -- bright purple -- and its kitchen turns out a terrific Caesar salad. Traditionalists may quibble that the greens are not tossed tableside, as Tijuana restaurateur Caesar Cardini purportedly intended them to be. Whatever -- it's rumored the original recipe didn't call for anchovies, either. Chacun à son gout, we always say. Here the dressing is suitably tangy, a fine foil for the fresh romaine, which is presented in whole-leaf form, rather than torn -- or, more heinously, hacked to death with a knife.