Remove the husks and rinse the tomatillos. Cut them in halves or quarters.

Rinse the chiles and cut off the stems. If you are going for a spicy version, use all 4 chiles. Depending on how mild you want it, you might use only 1 chile.

Rinse the cilantro and cut off the bottoms of the stems.

Place the tomatillos, chiles, and cilantro in a large blender with 1 cup water and ½ tablespoon salt. Blend completely and set aside.

Cut the onion in thin slices. Heat the olive oil in a large pot over medium heat. Add onion and sauté until transparent and edges begin to caramelize.

Place the chicharrón in the pot with the onions. Stir gently for a couple of minutes while the chicharrónes sauté.

Pour the tomatillo mixture into the pot and mix everything gently. Reduce the heat to medium-low and let it simmer for 20 minutes, uncovered. Stir every so often until the stew has thickened. Check the salt level and add more to taste.