There's a flighty kind of magic in the air at El Taco de Mexico on its best weekend mornings, something frail and almost inexplicable, moments when the swirling white church dresses and the tock of cleavers in the kitchen and the fast, hard-edged patter of Spanish at the counter all come together. The spell can easily be broken by a wrong word, a wrong order, just a momentary lull in the action. But even to someone coming down from a long drunk, the magic is discernable — particularly when that someone is returning to the living with each spoonful of menudo. This dish could be the world's greatest hangover cure. Hot and spicy, done soup-style with a thin, red broth full of soft tripe that turns electric with a spritz of fresh lime, this stuff can not only burn off the worst of last night's sins, but will get you back in shape to start sinning again.