Boil the meat for at least 2 hours until soft and brown. If you have time, then marinate it overnight.
Chop the boiled meat as finely as possible and fry in oil or beef fat in a pan. (Fry marinated meat in the same way, without boiling, then chop). Then return it back to the pan, salt and mix with the remaining fat and oil
Preheat the corn tortillas in a pan with a little oil. Put inside the filling. First meat, then chopped onions, cilantro, salt and salsa.