Peel and coarsely chop the onions
Peel the garlic
Heat a pot or pan on high heat
Sauté the onions and garlic for a couple of minutes – if using fresh tomatoes, halve them and sauté those as well. Everything can get some black spots
Remove the pot from the heat and transfer the vegetables to a blender
Add juice from ½ lime, cumin, fresh and ground coriander, and chipotle + some of the sauce it is in
Blend everything for 1-2 min. and pour it back into the pot
Let it simmer for 20 min. on medium-low heat
After the salsa has cooked, remove it from the heat and pour it into a bowl
Season with salt and sugar to taste