Heat oil in saucepan or skillet. Add onion; cook until soft. Crumble in the beef. Stir and fry until meat loses red color.
Sprinkle with salt and pepper. Pour in tomato sauce and water; bring to boil. Break spaghetti; sprinkle in a little at a time, stirring into sauce and keeping it separated.
Cover tightly. Simmer 20 to 30 minutes. Stir toward end of cooking time. Serve with cheese.Servings: 3 to 4