mushrooms and onion and cook, stirring until golden. Lift out and set aside. Add remaining 1/2 tb of butter to pan. Add beef strips and cook over high heat, turning meat and shaking pan, just until browned. Remove pan from heat, stir in reserved mushroom-onion mixture, salt, Worcestershire, paprika, pepper and sour cream. Return pan to low heat and cook, stirring constantly, just until sauce is heated through--do not boil. Sprinkle with parsley. Serve over noodles or rice.