Cut steak into 1-inch cubes and dredge with flour. Brown meat cubes on all sides in hot fat. Add water and salt. Simmer gently until meat is tender. Clean green peppers and cut into 1-inch squares. Boil 10 minutes and drain. Add pepper squares and pneapple chunks to browned meat. SAUCE: Combine cornstarch, pineapple juice, vinegar, sugar and soy sauce and cook until sauce is clear and thick. Pour sauce over meat mixture and simmer 5 minutes. Serve over Chinese noodles or cooked rice.