Place pork in a large ziploc bag and set in a shallow dish.
Whisk together orange juice, lemon juice, soy sauce, garlic, oregano, salt, and pepper in a small bowl.
Pour marinade over pork and seal the bag. Refrigerate for 3 to 24 hours.
Preheat oven to 375 F degrees.
Place pork in a baking dish and pour left over marinade over pork. Bake for 45 minutes to an hour.
Remove pork from baking dish and cover with aluminum foil. Let stand for 15 minutes before cutting.
Cuban Panini with Quick Pickles
In a small bowl combine cucumber, onion, lime juice, oregano, and sugar; set aside.
Cut the Ciabatta bread in half horizontally. Top one slice of bread with half of the cheese and all of the pork. Place cucumber mixture on pork. Top with the remaining cheese and the second bread slice.
Grill on a Panini maker for about 3 minutes or until grill marks form and the cheese has melted. Repeat with remaining ingredients.