Place chicharrones in a medium-size frying pan with one cup of water. Turn heat to low and allow to slowly simmer, and softening the pork skins-chicharrones. This way the chicharrones won’t absorb the liquid from the guajillo sauce.
Meanwhile, place the peppers in a bowl or saucepan and cover with hot water to soften for 20 to 25 minutes.The pork cracklings will keep softening, if you see that they need more water, add warm water, just enough to keep softening them.
Once the peppers are soft, drain and place into the blender with the garlic clove, the onion slices and one cup of water. Process until you have a sauce with a smooth texture.
Pour the sauce over the already softened pork crackling-chicharrones. Depending on your blender brand you will need to use a strainer to pour the sauce. Keep cooking for 10 minutes. After this time the salsa has reduced a little. Season the sauce with salt, pepper, and oregano.
Finally, stir in the cooked nopales; make sure they are well drained. And simmer for five more minutes.
Notes
You can learn how to clean and precook Nopales in the following link: How to cook Nopales