Step 1: Using the tip of a paring knife, make a series of 1/4 inch deep slits in the pork shoulder, 1 inch apart.
Step 2: Prepare the adobo: Stem the chiles, tear open, and remove the veins and seeds. Soak the chiles in water to cover until soft and pliable, about 20 minutes. Drain and place in a blender with the garlic, onion, oregano, cloves, allspice, cinnamon, salt, vinegar, and water. Puree to a smooth paste.
Step 3: Smear this paste all over the pork and let marinate for at least 4 hours, preferably overnight.
Step 4: Set up your grill for indirect grilling and preheat to 300 degrees F.
Step 5: Assemble the “consommé” (soup): Place the onion, carrots, zucchini, pumpkin, cabbage, tomato, potato, corn, herb bundle, and water in a large low round pot—a dutch oven is ideal. Use an old pan or one whose outside appearance you don’t particularly care about.
Step 6: You’re now ready to assemble the barbacoa: Place the consommé pot in the center of the grill away from the heat. Place a metal rack, like a cake rack, on top and layer it with half the avocado leaves. Place the pork on top, fat side up, and carpet it with the remaining avocado leaves. (If you don’t have a rack, you can place the avocado leaves right on top of the soup.) Do not replace the lid of the dutch oven, but tightly cover the smoker.
Step 7: Cook the barbacoa until the pork is fall-off-the-bone tender, 6 to 8 hours. The internal temperature will be about 180 degrees F. If using a charcoal grill, you’ll need to add 8 fresh coals per side every hour.
Step 8: To serve the barbacoa, discard the top layer of avocado leaves and transfer the pork and bottom layer of leaves to a platter and keep warm.
Step 9: Using a ladle, skim off any fat floating on the surface of the consommé. Stir in the chopped cilantro, chipotle, and salt and pepper to taste. The soup should be highly seasoned. Serve the consommé in bowls.
Step 10: Thinly slice the meat or cut it into chunks. Warm the tortillas on the grill or in a skillet. Enjoy the meat taco-style: on tortillas with shredded cabbage, cilantro sprigs, avocado, and salsa.
Serve with Salsa Borracha.