Rub salt on all sides of the pork and set it aside.
In a dry skillet over medium heat, add cumin, peppercorns, allspice, cloves and cinnamon stick. Toast for a minute or two until you can smell the cumin and pepper. Grind the toasted spices (I use a spice grinder or coffee grinder) to a powder.
In the same skillet, toast the garlic cloves until they’re charred all over, then add to a blender or food processor.
Transfer the toasted ground spices to the blender or food processor with the chile powder, oregano, achiote paste, citrus juices. Puree until smooth. Set aside.
Oven Method
Place a trivet or a ring of scrunched up aluminum foil in bottom of Dutch oven or cooking pot. Cut 2 pieces of kitchen twine or string twice the width of your pot. Lay them across the pot in a (+) orientation, like you're gifting wrapping a box.
Next, place two banana leaves in the pot, in a (+) orientation, like you're gift wrapping a box. Pour some of the marinade on the top of the banana leaves (center of pot), put the pork on top center. Pour the remaining marinade over the entire pork and carefully fold the banana leaves up and across the pork, like wrapping paper. Tie the kitchen twine together for a complete sealed package. Set the entire pot in the refrigerator for 4 hours minimum or overnight.
Take pot from refrigerator and set on counter for 15 minutes. Meanwhile preheat oven to 300°F. Pour a 1/2 cup of water into the Dutch oven or pot and cover with lid. Bake for 4 1/2 hours, or until the meat is very tender and pulls easily with a fork. For a 6 lb pork shoulder I have cooked for 5 1/2 hours.
Slow Cooker Method
Place a trivet or a ring of scrunched up aluminum foil in bottom of slow cooker. Cut 2 pieces of kitchen twine or string twice the length of your pot. Lay them across the pot in a (+) orientation, like you're gifting wrapping a box.
Next, place two banana leaves in the slow cooker, in a (+) orientation, like you're gift wrapping a box. Pour some of the marinade on the top of the banana leaves (center of pot), put the pork on top center. Pour the remaining marinade over the entire pork and carefully fold the banana leaves up and across the pork, like wrapping paper. Tie the kitchen twine together for a complete sealed package. Set the entire pot in the refrigerator for 4 hours minimum or overnight.
Take pot from refrigerator and set on counter for 15 minutes. Pour a 1/2 cup of water into the slow cooker and cover with lid. Cook on Low for 8 hours, or until the meat is very tender and pulls easily with a fork.
Serving
While the meat is still warm, carefully transfer the parcel to a serving dish. Use tongs or forks, shred the meat and spoon the cooking juices over meat. Serve with warmed tortillas, beans, pickled onions, cilantro and limes.
Video
Notes
I use kosher salt, typically 1 tsp per pound of pork.
Before wrapping the meat in the banana leaves, you must heat the banana leaves, either over a gas flame or under the broiler, until they soften. You can do this gently, just until the leaves are flexible. You can easily freeze any extra for another use, too. Look in the frozen food section of a local Mexican or Asian store. A substitute for the banana leaves can be parchment paper.