Preheat the pellet grill to 225 degrees Fahrenheit. Put the orange juice, lime juice and garlic into a large grill safe disposable pan. Add thinly sliced onions to the pan.
Carefully remove the pan from the grill and place pork shoulder on a cutting board. Cut the meat into 2-3 inch pieces, being sure to keep the pieces evenly sized. Return the pork chunks to the pan.
Cover the pan with aluminum foil and return to the pellet grill. Turn the temperature up to 350 degrees F and cook for about 2 hours until the meat reaches an internal temperature of 195 degrees F.
Skim off the fat from the top and remove any fat from the pan. drizzle some olive oil in a cast iron skillet. Heat the pan on your stove top over medium-high heat or place it back on the smoker at a temperature of 400 degrees Fahrenheit.
When the oil is hot, place the smoked pulled pork along with reserved juices in the skillet. Cook until the bottom of the meat is browned. Serve with tortillas and toppings.