Prepare the pork shoulder by cutting it into one-inch cubes. Add them to a large bowl and season with the cumin, salt and pepper. Mix to coat the meat, and then set it aside. (I put mine in a covered container in the fridge over night.)

Husk the tomatillos and slice the stems off the peppers and give them all a good rinse. Also cut the onion in half, and add the tomatillos, peppers and onion to a large stockpot, covering them with water. Boil for about 8 minutes, and then remove them with a slotted spoon directly into a blender or food processor, along with the garlic and cilantro, blending until the mixture is smooth.

Set the sauce aside.

Heat the oil over medium heat in a large Dutch oven with a lid, and saute the pork cubes on all sides (do this in batches), just until each side has some nice color on it.

Add all the pork back into the pot, along with all but one cup of the sauce, and stir to coat.

Bring the mixture to a boil, and then reduce the heat to a simmer. Place the lid on the pot and cook for about three hours (stirring occasionally) or until the pork reaches an internal temperature of 180 to 190 degrees.

While the pork cooks, cube some Russet potatoes into one-inch pieces, and boil them until they are fork tender. Drain them and set them aside.

When the pork is done, add in the potatoes and the rest of the sauce, and stir to combine. Add more salt and pepper, to taste.

Serve with tortilla chips, with corn or flour tortillas or just in a bowl.