Place the pork in a slow-cooker, add onion, orange juice, lime juice, garlic, salt, pepper, and cumin.
Cook on high 5 hours or low 8 hours. It will be done when the pork easily pulls away from the bone. Remove pork from the cooker and shred using two forks. Discard fat and bone.
OR TO GRILL PORK TENDERLOIN
Marinate tenderloin in the onion, orange juice, lime juice, garlic, salt, pepper, and cumin ideally for 4 hours.
Heat grill to 350°F. Remove tenderloin from marinade and discard marinade. Grill tenderloin on medium-high heat (350) with the lid on. Grill for 3 to 4 minutes turning once. Grill an additional 3 to 4 minutes.
Remove tenderloin from grill and allow to rest and cool 5 minutes before cutting.
CUBAN SANDWICH
Spread 1 tablespoon of yellow mustard on the inside of each piece of bread.
On the bottom half of each bun layer pork, ham, cheese, pickle, and top half of bun.
Heat a griddle or panini press. Heat the sandwiches until golden brown and the cheese is melted. Transfer to a cutting board and cut each one in half on a bias, then serve.