Tlalpan Public Markets number some 20 in total, not including the weekly tianguis and street markets. They're some of the finest places to eat in Mexico City, too. And while Tlalpan used to be a town far off to the south, today it's an integral part of Mexico City. The famous Mercado la Paz began there, more than a hundred years ago, in what was then still called San Agustin de las Cuevas.
Today, the Public Markets of Tlalpan are an integral part of life in the south of the City. All of them feature fresh food, and much of it locally sourced.
But most important for taco-laden international visitors, eating at the market also means fresh prepared food. Not restaurant food either. Check out the Fonda eating guide here, and visit the markets below. There's one near you, and they're always the freshest places to eat.