2 pounds pork shoulder, without bone but with some fat, butt, or country-style spareribs
Hot water to cover
Lard or olive oil as necessary
5 chiles anchos or chile guajillo, dried
4 cloves garlic, peeled
1/8 teaspoon cumin seeds
1/4 teaspoon oregano
1/2 cup vinegar
1 teaspoon salt
Prepare the sauce. Slit the chilies open. Remove the seeds and veins, and cover them with hot water and soak for 15 minutes, then remove with a slotted spoon and transfer to the blender jar and blend until smooth with the rest of the ingredients. The sauce should be thick, more like a paste. You will have to keep stopping the blender to release the blades.
Cut the meat, with the fat, into 1 inch cubes. Place in large pot with a heavy bottom. Barely cover the meat with water, add the salt, and bring it to a boil, uncovered. Lower the flame and let the meat continue cooking briskly until all the water has evaporated—about 45 minutes. Do not add too much water at the beginning or the meat will fall apart while frying. There should be about 1/4 cup of fat in the dish in which the meat was cooked; if not, make up to that amount with lard. If the meat is still fairly hard when the water has evaporated, then add a little more water and continue cooking.
Now fry the meat in the remaining oil until brown, turning continually. The meat will get more evenly cooked if the pan is rather large and shallow. Remove the meat from the dish and pound it until it is in shreds in a molcajete, shred it finely with two forks, or mash with the back of a heavy spoon.
Mix the meat and chili sauce. Cook the mixture over a low flame for 15 to 20 minutes, or until the meat is well seasoned and the mixture rather dry, scraping the bottom of the dish so the sauce does not stick.
You can make a lot of it at one time; it will keep for a very long time in the refrigerator, or you can freeze it. It is great for tacos or burritos.