Cook pork mixture 30 minutes. Place in labeled airtight 2-quart freezer container. Freeze no longer than 2 months. About 30 minutes before serving, dip container into hot water to loosen; remove container. Cover and heat pork mixture to boiling in 3-quart saucepan over medium heat, turning and strirring frequently. Mix sour cream and flour; stir into pork mixture. Heat to boiling, stirring constantly. Boil and stir 1 minute. Stir in tomatoes; heat through. Serve over noodles.
Add bright color and flavor to this dish by stirring chopped green, red or yellow bell peppers into the mushroom and onion mixture.
Pork is easier to cut if partially frozen, about 30 to 60 minutes.