In a blender, combine pineapple juice, achiote paste, garlic, cider vinegar, oregano, cumin, salt, and black pepper. Blend until smooth.

Place the pork slices in a large bowl and pour the marinade over them. Mix well to ensure all pieces are coated. Cover and refrigerate for at least 2 hours, preferably overnight.

Preheat the grill to medium-high heat. Thread the marinated pork onto skewers.

Grill the skewers for about 10-15 minutes, turning occasionally, until the pork is cooked through and has nice char marks.

Remove from the grill and let rest for a few minutes before slicing into small pieces.

Warm the corn tortillas on the grill for about 30 seconds on each side.

Fill each tortilla with grilled pork, diced pineapple, chopped onion, and cilantro. Serve with lime wedges on the side.