In a dry skillet over medium heat, toast the guajillo and ancho chiles until fragrant. Remove from heat and soak in hot water for about 15 minutes until softened. Drain and blend with garlic, cumin, oregano, salt, black pepper, and vinegar until smooth.

Marinate the Pork

In a large bowl, combine the sliced pork with the marinade and diced pineapple. Mix well to coat the pork thoroughly. Cover and refrigerate for at least 2 hours, preferably overnight.

Cook the Pork

Preheat a grill or skillet over medium-high heat. Remove the pork from the marinade and discard the excess. Cook the pork for about 5-7 minutes on each side, or until well charred and cooked through.

Assemble the Tacos

Warm the corn tortillas on the grill or in a skillet. Fill each tortilla with the cooked pork, then top with chopped onion and cilantro. Serve with lime wedges on the side.