Combine the orange juice, soy sauce, lime juice, onions, garlic, oregano and ginger into a bowl. Stir well to combine.
Place the pork tenderloins in a large baking pan or a large zip-close bag. Pour the marinade over the pork, cover and place in the fridge. Marinate for at least 4 hours or overnight.
Set the slow cooker to warm and remove the tenderloins from the fridge. Pat the pork dry and place in the slow cooker. Cook on high for 3 to 4 hours or on low for 6 to 8 hours (until tender and reaches 145 degrees).
Pour the marinade in a saucepan, bring to a boil for 5 minutes, and then set aside.
When the pork is finished cooking, shred the meat in the slow cooker and pour the remaining sauce over the shredded pork. Turn the pork to coat and serve warm with cooked rice, mashed potatoes or on slider buns with cheese.