You can either roast the meat in an oven or put it in a crock pot on low for 12 hours. If you go the oven route, set the temperature to 200 degrees and simply put the meat in a roasting pan with a lid or cover with foil. Do not add salt or water or anything. Just the meat. Same story with the crock pot, just the meat!
Once the meat is cooked, drain the meat and reserve the juices. Cool the mean, then shred. I do this step in my Kitchenaid mixer.
Melt the shortening in a large skillet, then add the onions and the chilis. Sautee one minute. Add salsa, garlic, flour, salt, and cumin. Cook one minute over meduim-low heat. Then add shredded meat and juices to skillet. Cook 5 minteus until thick.
Place half a cup of meat in the center of a tortilla (warm them in the microwave to make them more pliable). Fold tortilla like an envelope around the meat. Either bake them at 375 until golden (a little healtheir), or secure them with toothpicks and fry them in oil (a little yummier). Serve hot with lettuce, guacamole, tomatoes, salsa and sour cream.