What is "suadero"

Suadero, in Mexican cuisine, is a thin cut of beef from the intermediate part of the cow between the belly and the leg. Suadero is noted for having a smooth texture rather than a muscle grain. Typically, suadero is fried and used as a taco filling. Suadero, also known as matambre, is the name of a very thin cut of beef in Argentina, Paraguay and Uruguay, taken from between the skin and the ribs,[1] a sort of flank steak.