In a medium bowl, combine orange juice, lime juice, minced garlic, olive oil, cumin, oregano, salt, and pepper to make the mojo marinade.
Place the pork in a large zip-top bag or a shallow dish and pour the marinade over the meat. Seal or cover and refrigerate for at least 4 hours, preferably overnight.
Preheat your oven to 325°F (160°C). Transfer the marinated pork to a roasting pan, and pour the marinade over the pork.
Roast uncovered for about 2.5 hours, or until the pork reaches an internal temperature of 190°F (88°C) and is tender enough to shred easily.
Remove pork from the oven and let it rest for 10 minutes before slicing or shredding.
Garnish with chopped cilantro before serving if desired.