Tacos de suadero

Suadero, in Mexican cuisine, is a thin cut of meat from the intermediate part of the cow or pig between the belly and the leg. Suadero is noted for having a smooth texture rather than a muscle grain. Typically, suadero is confited or fried and used as a taco filling. Suadero, also known as matambre in Argentina and sobrebarriga in Colombia, is the name of a very thin cut of beef in Argentina, Paraguay and Uruguay, taken from between the skin and the ribs, a sort of flank steak. In Mexico City, México, it is very common and popular, offered mainly on street taco stands, but also eaten in sandwiches and in a sort of round thick hollow fritter, made of corn dough, served hot, flat and filled with various meats, garnishes and sauces; these are called gorditas.

Source: Wikipedia