mushrooms and onion and cook, stirring until golden. Lift out and set aside. Add remaining half 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.