Guajillo chilies and roasted peanuts produce a rich, earthy sauce for thick-cut, bone-in pork chops. We especially liked the deep color and bright flavor of guajillo chilies, but New Mexico chilies were good, too. Whichever you use, look for pods that are soft and pliable, an indicator of freshness. The árbol chili supplies the heat; you can omit it if you like, or substitute ¼ to ½ teaspoon red pepper flakes (pepper flakes do not need to be toasted, so add them directly to the blender). You will need a 12-inch oven-safe skillet for this recipe.