Cut pork into tiny pieces. Brown in shortening; add chopped onion and tomatoes; stir together. Add flour slowly (do NOT use masa harina!). Stir till thickened as like gravy, then add 2 cups water. To suit, add: garlic powder, salt, pepper, liberal dose cumin. Stew on medium low for 3-45 minutes. Serve with refritos, Spanish rice.