Remove the pork from its package and place in the bottom of a 6 quart or larger slow cooker.
In a small bowl stir together the oregano, cumin, chili powder, salt, pepper, paprika, and cinnamon.
Season the pork evenly on all sides, rubbing the spice mixture into the meat.
Cut the oranges and limes in half and squeeze the juice out evenly over the meat.
Pour in the broth, and sprinkle in the onion and garlic.
Cover and cook on low for 8-10 hours until tender.
Once the meat is tender, preheat your oven broiler to high.
Shred the meat onto a large baking sheet and spread out in an even layer. Pour ½ cup of the juice from the slow cooker over the meat. Broil for 8-10 minutes until crisp. Drizzle with ¼ -½ cup more of the juices if desired.
Instant Pot Method:
Season the pork as listed above. Add the pork to the bottom of a 6 quart or larger instant pot (see note for liquid).
Squeeze the orange and lime juices over the meat, then add in the broth, onions, and garlic.
Place the lid on the pot and set the valve to sealing position. Cook on either the MANUAL or MEAT setting at 15 minutes per pound of meat. (60 minutes for 4 pounds).
Once the cooking time is up, allow the pot to come to pressure naturally. Once the pressure has gone down completely, open the sealing valve. Remove the meat from the pot and shred. Follow step 8 from above to crisp the carnitas in the oven if desired.
NOTE ON INSTANT POT METHOD: If you are using an instant pot, you need to add 2 cups of broth to the pot for this recipe instead of 1. Keep in mind that your pot takes time to come to pressure, and natural release so total cooking time will be about 2 hours.NOTE ON SERVING CARNITAS: You can scroll up above the recipe card to see a list of our favorite ways to serve this dish!