Melt butter in small skillet over medium high heat.
Add onions; cook and stir until tender.
Place onions, meat, rice, egg and seasoning in large bowl.
Add water; mix until well blended. Shape into medium-sized meatballs.
Pour spaghetti sauce into skillet. Bring to boil; add meatballs. Return to boil. Reduce heat to low; cover. Simmer 15 minutes or until meatballs are cooked through.