I used to make a similar recipe with beef, but I switched to pork when we lived in Singapore for 3 years. Beef was expensive and not very good there. We like it so much with pork, we never switched back.
1 pork tenderloin (3/4 pound), cut into 1-inch pieces
1 teaspoon vegetable oil
1 small onion, chopped
2 garlic cloves, minced
1 can (8 ounces) tomato sauce
1 can (4 ounces) chopped green chiles
1 teaspoon chili powder
1/2 teaspoon salt
1/2 teaspoon dried oregano
1/2 teaspoon ground cumin
1/4 teaspoon pepper
2 to 4 flour tortillas (7 inches), warmed
Optional: Shredded lettuce and chopped tomato
In a skillet, brown pork in oil. Remove from pan and keep warm. In same skillet, saute onion and garlic in drippings until tender. Stir in the tomato sauce, chiles, chili powder, salt, oregano, cumin and pepper. Add pork; bring to a boil. Reduce heat; cover and simmer for 20 minutes or until pork is tender.
Cool slightly; shred with 2 forks. Return to sauce; heat through. Serve in tortillas with lettuce and tomato if desired.