REPARING THE SAUCE
Remove the stems and seeds from the ancho and pasilla chiles. Reserve the chipotle chile.
Roughly chop the onion.
Peel and crush the garlic.
Preheat 3 tablespoons of oil in a frying pan.
Fry the onion and garlic over medium heat for 2 minutes.
Add the tomatoes and dried chiles to the pan. Continue to cook over medium heat for 3 minutes. Do not add the chipotle yet.
Add just enou