The porteño aversion to anything spicy means there's just not a lot of demand for authentic Mexican fare. But María Félix probably comes the closest, serving an array of Mexican dishes with a touch of Tex-Mex. The food is fresh and vibrant and the flavors are remarkably varied, if lacking in that hit of heat. Asking for hot sauce doesn't result in anything much stronger on the table. Still, it makes a nice change from the usual local fare, and when you wash it down with a reasonably good margarita you won't leave with any complaints. Thursday through Saturday evenings there's a wandering mariachi band.