1. Preheat oven to 350. Lightly grease a 3 quart rectangular baking dish; set aside. In large skillet, cook beef and onion til meat is cooked through, breaking up meat as it cooks; drain off fat. Stir chili powder and cumin into meat mixture; cook and stir for 1 minute. Stir pinto beans and undrained chile peppers into meat mixture; set aside. Stir together sour cream, flour and garlic powder. Set aside.
2. Put half of the tortillas in prepared baking dish, cutting to fit and overlapping as needed. Top with half of the meat mixture, half of the sour cream mixture and half of the enchilada sauce; repeat layers. Cover dish with foil.
3. Bake for 35 to 40 minutes or til heated through. Uncover; sprinkle with cheese. Bake for 5 minutes or til cheese melts. If desired, garnish with chopped tomato and sliced green onion. Makes 12 servings.