Step 1
Combine the orange juice lime juice, achiote paste, garlic, cumin, oregano, salt, and allspice in a blender. Then add to a large ziploc bag or non-reactive bowl. Add the pork and marinate for at least 1 hour or overnight.
Step 2
Slow Cooker: Add the marinated pork, bay leaf, and marinade to the slow cooker. Cook on low for 8 hours until the pork is fork tender. Shred with 2 forks and let sit in the slow cooker in the juices for 15-30 minutes if possible.
Step 3
Oven Method: Preheat the oven to 325 degrees. Line a large baking dish with a couple of layers of foil. Add the pork and bay leaf. Then seal the aluminum foil tightly. Cook for 3-4 hours until the pork is fork tender. Shred.
Step 4
Instant Pot: Add the pork, bay leaf, and marinade to the Instant Pot. Use the Manual setting for 45 minutes. Then let naturally release for at least 15 minutes Shred with two forks.