Grill or pan-fry the meatballs until brown. Put them aside.
Finely chop the onion and garlic.
Heat a spoonful of oil in a casserole dish, and soften the onion. Add the garlic and stir for a minute or so.
Add the tomato purée, stir then pour in the chopped tomatoes. Cook for about 15-20 minutes until you get a thick sauce. Add most the herbs, season to taste and pulse with hand-held blender.
Add the meatballs. Cover and simmer for another 15 minutes or so.
Serve with pasta and the remaining herbs. You can also scatter some grated Parmesan or other cheese on the top if you like.