A fish taco is serious business. There are so many ways to screw it up, so many ways to do it wrong, and -- in our judgment, anyhow -- a strict set of rules for doing it right. Jalapeño Mexican Grill does it very, very right. It starts with batter-dipped and fried chunks of mild, fresh whitefish on a thick flour tortilla, adds shredded cabbage (not lettuce) and a few soft, incredibly ripe pieces of tomato, and laces the whole thing with a thin, chilled buttermilk ranch sauce. Add a couple wedges of fresh lime and you've got the closest thing Denver has to the beachside grub served all along coastal Mexico. Simple, quick, cheap and delicious.