If working with fresh tomatoes, use a cheese grater to grate them to a pulp, discarding the skin.
Place your tagine base, or pan, over a medium to low heat with the oil. Once heated, sauté the diced capsicum and onion for several minutes, before adding the garlic for just 1-2 minutes more.
Add your tomatoes, and stir in all the herbs and spices. Bring to a simmer, then cover and cook until the tomatoes cook down and the sauce thickens, for around 45 minutes, checking every 10-15 mins or so to give it a stir and mash the tomatoes down with the back of your stirring spoon, and adding water if necessary.
When the sauce is thick enough, give it a taste and adjust seasoning as desired. Now, add the meatballs, cover and continue to cook until the meatballs are cooked through for a further 10 mins