Heat the oil in a medium, non-stick frying pan at medium high heat and add the onion and garlic clove. Cook them for 2 minutes before adding the pasilla chillies cut into 3 pieces; stir continuously and cook for 1 further minute. Remove from heat and take the contents of the pan, leaving the oily pan aside to use later.
Transfer the pan fried items to the blender together with the beans, water and chipotle in adobo. Blend until you have a smooth, silky sauce.
Return the oily pan to the heat at medium high. Pour the bean sauce making sure to scrap all of the beans from the blender, you can use a little extra water to dislodge anything stuck in it.
Cook the beans on medium high heat for 10 to 15 minutes, stirring constantly to prevent them from sticking and burning. You’re looking for a custard like consistency in them.
While the beans cook, get on with cooking the chorizo. Heat the oil in a small, non-stick frying pan to medium high heat. Add the chorizo and fry for 2 minutes or until the chorizo has released its juices. Add the onion and chilli and lower the heat to medium. Cook this stirring occasionally for 4 to 5 minutes, or until the chorizo starts to crisp up a little and the onion and chilli are soft
To serve these tacos, take a warmed corn tortilla, add a spoonful of the refried beans and top them up with some chorizo. Sprinkle some feta cheese and some salsa of your choice and enjoy.