St. Paul's West Side is ground zero for Mexican and Mexican-American cuisine. The institutions there are beloved enough to provoke diners to fisticuffs over which of their favorites is best. Now we're heading just south to Taco Libre in West St. Paul, for the next evolution of the taco. Taking inspiration from Mexico City (its owners hail from that great food metropolis), the menu reflects the innovative resourcefulness of street meat tacos. Go to any city in Mexico, and your best taco is going to be the one that you get from the cart outside of the bus station. At Taco Libre, they've made that taco-cart taco the muse of their restaurant, without stripping it of any of its soul. Profound and tender tripe, decadent whole filets of asada, papas con chorizo frizzled until caramelized and crisp at the edges — 17 choices means you can go on like this for half the month, then start all over again. Beautifully grilled corn tortillas sell themselves, and salsas available in hot and hotter are worthy of deference and awe.