Blend achiote paste, bitter orange juice, garlic cloves, cumin, oregano, and salt until smooth. Score pork shoulder in a 1-inch crosshatch pattern and rub marinade onto all surfaces. Marinate in refrigerator for 1 to 24 hours.
4 oz achiote paste, 1 cup bitter orange juice, 6 cloves garlic, 2 tsp cumin, 2 tsp oregano, 2 tsp salt, 4 lbs pork shoulder
Preheat oven to 325°F (163°C). Pass banana leaves over open flame for 10 seconds to soften and release aroma. Layer softened banana leaves inside a Dutch oven, overlapping edges. Spread sliced white onion over the leaves.
5 leaves banana leaves, 1 whole white onion
Place marinated pork shoulder over the bed of onions. Fold banana leaves over pork to completely seal it. Cover the Dutch oven with its lid or seal tightly with heavy-duty foil.
4 lbs pork shoulder, 5 leaves banana leaves, 1 whole white onion
Roast in preheated oven for 3 to 4 hours until internal temperature reaches 195-205°F (90-96°C) and pork shreds easily with a fork. Begin checking for doneness at 3 hours; if not tender, continue roasting in 30-minute increments.
4 lbs pork shoulder
Remove pork from oven and keep wrapped. Let rest for 15 minutes to redistribute juices. Carefully unwrap to avoid steam burns and transfer pork to cutting board. Shred pork into medium-fine pieces with two forks and mix with pan juices before serving.
4 lbs pork shoulder
