Cut the pork shoulder into 1-inch cubes, season with the kosher salt and pepper. Set aside.
Remove the stems (and seeds if you want it milder in heat), from the anchos, pasillas, and guajillos. Cover chiles with 1 cup boiling water and let them steam for about 30 minutes until they are tender.
Put the chiles, soaking liquid and 2 cups of the chicken stock, garlic, onion, jalapeño, chimayo chili powder, cumin and Mexican oregano (cayenne is optional for more heat) into a blender and purée until smooth. Set aside.
Brown the pork in a large, stock pot over medium heat with oil.
Add 4 cups of chicken stock and simmer on low covered for one hour. Stir in the potatoes (optional) and chile purée. Simmer uncovered for another 45 minutes or until the meat is tender and the sauce is a thick, deep red color. Season with additional salt if needed. Serve with warm tortillas.
This is a bright red, sweet and earthy flavored New Mexico chile, and worth trying to find or order online. Otherwise, substitute your favorite chili powder or make my recipe for homemade chili powder.
Mexican oregano has notes of mild licorice and citrus. Mediterranean oregano is a member of the mint family and most often is used in Greek and Italian recipes. Mediterranean oregano is the one most found in spice racks and supermarkets.