Sauté the onions in oil in a saucepan until clear. Then add in the tomatoes.
Spice with all the spices and cook the tomatoes until fully disintigrated.
Lower flame and cover and cook for 20 minutes. Stir sparingly.
Cook the sauce with whichever meatballs you use for 40 minutes on low and covered. This will fully infuse the meatballs with the sauce.