Slice the pork into thin ¼-inch pieces using a sharp knife. Place the slices in a large bowl.

Boil water in a pot and add the guajillo chiles. Cover and let them soak for about 5 minutes until they soften. Remove the chiles, cut off the seeds and stems, and set them aside. Gloves are recommended for this step.

Combine the guajillo chiles, orange juice, lime juice, onion, cinnamon, pepper, Mexican oregano, cumin, achiote paste, and salt in a blender. Blend until smooth. If the mixture is too thick, add some of the hot water used to soak the chiles and blend again.

Pour the marinade over the pork slices and mix thoroughly. Cover the bowl with plastic wrap and refrigerate for at least 4 hours or overnight. Take the meat out of the refrigerator 30 minutes before cooking.

Preheat the oven to 450°F. Line a baking pan narrower than your skewers with aluminum foil, allowing the skewers to rest on the edges of the pan. A 9x13 inch pan works well with 12-inch skewers.

Drizzle olive oil over the meat and bake for about 30 minutes until the surface browns and chars. You may need to turn on the broiler for more charred bits. Baste the meat with pan juices during cooking.

Allow the cooked meat to rest for 5 minutes before cutting it into bite-sized pieces.

Serve the pork in tacos with grilled pineapple, fresh cilantro, red onion, salsa, and lime wedges.