For authentic Mexican food in a lively atmosphere, try this Clark Street spot. On weekends, Frontera is always packed, but people do not seem to mind the wait. If you are lucky, you can grab a small table at the bar section and start on drinks and appetizers before you are seated. Basic margaritas are quite pricey, but you can try fancier varieties for a few bucks more. The Queso Fundido is good eating—a spicy cheese and onion dish wrapped in hot tortillas.