La Abuelita in the Mercado 20 de Noviembre in Central Oaxaca prepares a perfect open-faced tlayuda. The crisp fried tortilla is smeared with pork lard and black bean paste, and then topped with fresh quesillo - string cheese - avocados, shredded cabbage and bright red, picante chorizo. Spread the chorizo around to take advantage of the spicy and savory taste with every bite