Place pork butt, yellow onions, crushed garlic, cumin, bay leaves, Mexican oregano, salt, black peppercorns, and cayenne in a large pot and cover with water by 1 inch. Bring to a boil.
Lower the heat to medium-low and simmer until tender, about 45 minutes, skimming the surface to remove any impurities (foam) that form. Remove the bay leaves.
Using an immersion (stick) blender or blender, blend the tomatillos and roasted peppers. Combine with the liquid left over from cooking the pork (including onion and peppercorns) and blend until smooth.
Shred or cube the pork and return it to the pot containing the blended and roasted peppers. Add chicken stock and remaining spices. Bring to a simmer over medium-low heat for at least 20 minutes. The longer you allow it to simmer, the better the flavors combine. If it gets too thick, add water or additional chicken stock. I know mine simmered for 2 hours.
Stir in fresh cilantro right before serving. Garnish with your choice of avocado, tomatoes, Queso Fresco, tortillas, and additional chopped cilantro.
Notes
We now use canned tomatillos and roasted peppers. These instructions are provided if you choose to roast your own."Place peppers and tomatillos on a foil-lined baking sheet. Place under a broiler and watch carefully. When skins blister and turn dark, turn until each side is browned. Remove from the oven and put peppers in a glass bowl. Immediately cover the bowl with plastic wrap. Let sit for 15 minutes. The steam will help remove the skin. Under running water, remove the tops, skins, and seeds from the peppers. Remove the tomatillo skin and stems but you will want the insides including the seeds."
This recipe was calculated using the exact brands and measurements I used to make this recipe. If you are following a strict diet please note changing anything will cause the nutritional info to change. My calculations are intended as a guide only.