Top 5 Restaurants is tracking down the top spots for America's favorite food import — the taco. Crunchy fish, succulent pork, savory slow-cooked steak: Everything tastes better wrapped in a tortilla and served up with passion. Meet a dedicated sister act in Texas, a one-man wonder staked out in an East Los Angeles parking lot, and a father and son institution in San Francisco, all dishing out food fit for a five-star restaurant.