Pickle the onions: In a small bowl, add enough lime juice to submerge the red onion. Set aside while you prepare the re-fried beans.
Make the refried beans: Heat oil (or lard) in a sauté pan, and sauté onion and garlic until translucent.
Add chilies and spices (if using), then stir in beans, and some bean broth.
Simmer the beans, and mash into a creamy puree until it reaches your desired consistency.
You can puree in the blender too, for a super-smooth sauce (just make sure to remove the whole chile).
Add more broth as needed and season with salt.
Remove from the heat, then top with pickled onions and cilantro.
