2Toast spices: In a dry pan over medium heat, lightly toast Cumin seeds, Black peppercorns, Cloves, and Mexican cinnamon stick until fragrant, about 1-2 minutes. Be careful not to burn them.
3Prepare the marinade: Drain the softened Guajillo chiles and Ancho chiles, reserving a small amount of the soaking liquid if needed. Combine the rehydrated chiles, toasted Cumin seeds, Black peppercorns, Cloves, Mexican cinnamon stick, Garlic, Mexican oregano, Apple cider vinegar, and Salt in a blender. Blend until a smooth paste forms, adding a tablespoon or two of the reserved chile soaking liquid if necessary to achieve a smooth consistency.