
Add the achiote paste, orange juice, lime juice, onion, garlic, salt, and cumin to a large blender. Blend until smooth.
Add the cut pork shoulder to a large bowl or baking dish and pour the blended marinade on top. Toss together until evenly coated. Cover with plastic wrap and marinate in the refrigerator for at least 6 hours, and up to 24 hours.
Preheat oven to 325℉. Place the banana leaves in a Dutch oven so that the bottom is completely covered and the leaves are hanging over the sides.
Pour the marinated pork, including all of the marinade juices, into the Dutch oven, then fold in the banana leaves so they completely cover the meat.
Cover and bake for 3 ½ hours, or until the pork is pull-apart tender. (See Notes for other cooking methods)
Remove from the oven and transfer the pork into a bowl with a slotted spoon.
Shred the meat with a fork and add in ⅓ cup of the cooking liquid.
Serve in tacos with warm corn tortillas, pickled red onion, queso fresco, and chopped cilantro.