Although St. Louis has a modest Mexican population and a number of popular restaurants of that ethnic persuasion, this is a tough town in which to find truly great renditions of all your Mexican favorites under one roof. To satisfy a refried craving, you have to hunt and peck -- this place for pollo en mole, that place for killer guacamole. Seems like every place in town serves a clunker or two that offends a palate accustomed to fare from the Texas border -- mole sauce that tastes like Hershey's Kisses; tongue taquitos with the rubbery consistency of raw squid. But we've found a place that almost hits on all eight cylinders. El Vaquero has been in business for almost a year-and-a-half. Nothing fancy about the strictly-from-Formica place. But the food is authentic Mexican -- guacamole that's spicy and leavened with onions and sweet peppers but isn't overly salty; taquitos that bring back memories of streetside stands in Piedras Negras, including tongue that's firm but not vulcanized. And the mole sauce has smoke and just enough fire to please, with the chocolate as unsweetened baseline.