Finely chop the onion and garlic.
Heat the oil in a large saucepan and gently sauté the chopped vegetables until soft.
Meanwhile, peel and dice the sweet potatoes and carrots. Chop the red peppers.
Add these to the pot, stir for another minute then add the spices & chipotle paste and/or tomato purée.
Add the tinned tomatoes and enough water to cover the vegetables, then add the stock powder.
Bring to the boil, cover, turn down the heat and cook for 20 minutes or until the vegetables become tender.
Turn off the heat. Remove the bay leaf. Add the coriander leaves. Season to taste, then pulse with a stick blender until you get a thick, smooth sauce.
Meanwhile, grill, pan/fry or bake the meatballs, following the packet’s instruction.
Also, cook some rice, pasta or noodles, then serve this with the sauce, topped with the meatballs.
You can use any remaining sauce for other dishes (such as pasta).