Toast the stems and seeds from the Dried Guajillo Chiles quickly in a dry skillet until fragrant (about 30–60 seconds), then soak them in hot water for 20 minutes until soft; reserve ½ cup of the soaking liquid.
In a blender combine the softened chiles, a couple tablespoons of Achiote Paste, ½ cup Pineapple Juice, 2 tablespoons White Vinegar, 3 peeled Garlic Cloves, one roughly chopped White Onion, 1 teaspoon Mexican Oregano, 1 teaspoon Ground Cumin, ½ teaspoon Ground Black Pepper, a pinch of Ground Cloves, ¼ teaspoon Ground Cinnamon and 1–2 teaspoons Kosher Salt; add some of the reserved chile soaking liquid as needed and blend to a smooth, thick paste.
Trim any excess fat from the Pork Shoulder and cut into ¾–1 inch thick slices or large chunks so the marinade can penetrate; place the pork in a bowl or zip‑top bag and pour the marinade over it, massaging to coat thoroughly. Cover and refrigerate at least 4 hours, preferably overnight, for best flavor.
To cook, preheat your oven to 425°F (220°C) if roasting, or heat a heavy skillet or grill to high if you prefer to sear. If roasting, arrange the marinated pork on a rack over a rimmed baking sheet and roast 25–35 minutes until edges are caramelized and the meat reaches about 160°F, turning once; if searing, heat a tablespoon or two of Lard in the skillet and cook the slices in batches until deeply browned and cooked through.
If you like caramelized pineapple, add slices of Pineapple to the pan or baking sheet during the last 8–10 minutes of cooking so they char lightly and concentrate their sweetness.
Once cooked, let the pork rest 5 minutes, then thinly slice or chop it into bite‑sized pieces; mix in a few pieces of the roasted Pineapple so each taco gets a sweet, tangy note.
Warm the Corn Tortillas on a dry skillet or comal until pliable and lightly charred at the edges.
Assemble tacos by piling the sliced pork onto the warm tortillas, topping with some diced White Onion (if you didn’t use the roasted pineapple for garnish), chopped Cilantro, a squeeze of Limes and a spoonful of Salsa Roja.
Serve immediately so the tortillas stay warm and the pork remains juicy and slightly crisp at the edges; pass extra lime wedges and salsa at the table.
