Remove the stems and seeds from 6 dried guajillo chiles and 2 dried chiles de árbol and place them into a wide glass bowl
Cover the chilies with boiling water and let them sit for 20 minutes
Combine all of the marinade ingredients (including the rehydrated chilies) into a large blender or food processor and pulse until smooth
Cube a 3 pound pork shoulder, transfer into a large glass bowl and add the marinade ensuring that all of the pork is coated
Cover the bowl tightly and chill for at least 90 minutes or overnight
Preheat your oven to 325 degrees
Transfer the pork and marinade into a greased braising pan, Dutch oven or deep baking dish and cover the pot
Braise the pork covered at 325 degrees on a center rack for 3 hours
Before the pork is done braising, thinly slice 2 large sweet bell peppers, 1/2 of a white onion and 1/2 of a pineapple
Carefully remove the pork (increase the oven temperature to 375°), shred the pork and add back into the sauce
Add the thinly sliced peppers, onion and pineapple, mix and braise uncovered for 30 minutes at 375°
Enjoy with tortillas, cilantro and additional diced pineapple and onions