In a large mixing bowl, COMBINE ground beef, salt, garlic powder, Italian seasoning, pepper, onion salt, chopped onion and Parmesan cheese.
MIX thoroughly; ROLL into 1-inch balls (3 to 4 meatballs per serving).
BROWN in a lightly greased skillet or BROIL in oven until brown but not dry, about 10 minutes.
DRAIN off excess fat; PLACE meatballs in a casserole dish.
TOP with green pepper strips, sliced mushrooms and onion rings.
POUR tomato sauce over ingredients.
COVER; BAKE at 375° until sauce has come to a boil, about 15-18 minutes.
SERVE over cooked spaghetti.
Per Serving (excluding unknown items): 712 Calories; 34g Fat (39.5% calories from fat); 36g Protein; 80g Carbohydrate; 16g Dietary Fiber; 100mg Cholesterol; 6470mg Sodium. Exchanges: 0 Grain(Starch); 3 Lean Meat; 13 Vegetable; 4 1/2 Fat; 0 Other Carbohydrates.