Common throughout the Southwest in home cooking but not so common in restaurants (who knows why?), this savory shredded meat burrito is a meal in itself. The word machaca is derived from the Spanish machacar, to pound, an apt description of the appearance of the meat. This recipe is from our late friend, Barbara Graham.
Place the roast in a large pan with water to cover and simmer until tender and the meat begins to fall apart, about 3 to 4 hours. Remove the roast from the pan, remove the fat and bone, and shred the meat by hand or with a fork.
Return the meat to the pan, add the remaining ingredients, stir well, and simmer until all the liquid has been absorbed by the meat. Place the meat in a large flour tortillas with the tomato, lettuce, cheese, and sour cream, if used.