Cut the pork into 2" pieces and place them in the Instant Pot.
Combine all the spices and sprinkle them over the meat.
Place the orange and lime slices on top of the meat.
Seal the pressure cooker and set it to manual high pressure for 35 minutes.
Once done cooking, allow the pressure to release naturally, which takes about 20 minutes.
Using two forks, shred the meat and spread it on a baking sheet.
Preheat the broiler to 500°F. Broil for 5-10 minutes, or until crisp if desired.
Notes
Serve immediately in tacos, burritos, salads, or over rice. For extra crispiness, you can skip the broiling step and let the carnitas cool slightly before shredding, then pan-fry them in a hot skillet with a little oil.