I'm seeking a better-than-decent taco joint (or taco/burrito/Mexican joint) in the Concord-Pleasant Hill-Walnut Creek area. Some place that doesn't throw 4 oz. of whipped green colored sour cream "guacamole" on a stale flour tortilla and call it a quesadilla. A place with fresh(er) lime wedges, roasted hot peppers, and a license to sell beer (and is open at night). Any suggestions? Authenticity is more important to me than atmosphere.
Thanks in advance for any recommendations --