In a blender or food processor, combine: Achiote paste, citrus juice (bitter orange, or orange + lemon), Oregano. Blend until smooth.

Place the pork in a large bowl and add the minced garlic, shredded onion, salt and pepper, the achiote marinade

Mix well, cover, and refrigerate for at least 2 hours, or overnight for best flavor.

Preheat your oven to 400°F. Place the marinated pork, adding all the marinade, in an oven-safe dish or Dutch oven. Cover tightly with foil or a lid, and bake for 2 and a half hours, or until tender and easy to shred.

Taste and adjust seasoning if needed.

Once fully cooked, use two forks to shred the pork. You should be left with juicy, richly-colored meat that practically melts in your mouth. Serve over a corn tortilla and topped with red pickled onion and a tangy, citrus and spicy habanero salsa.