3While the pork browns, prepare the chiles. Remove stems and seeds from the Ancho chiles, Guajillo chiles, Pasilla chiles, and Arbol chiles. Briefly toast the chiles in a dry comal or skillet over medium heat for 30 seconds per side until fragrant, being careful not to burn them. Transfer the toasted chiles to a bowl and cover with hot water to rehydrate for 20 minutes.