Step 1
Trim excess fat from the pork shoulder and cut it into a few large pieces. Coat the pork in a spice rub with chili powder, cumin, oregano, salt, and pepper, then add lime juice, orange juice, onion, and garlic.
Step 2
For the slow cooker, cook the pork on low for about 8 hours until it's fork-tender. For the Instant Pot, use the meat setting on high pressure for 30 minutes, then let it naturally release.
Step 3
Shred the carnitas in the post. For crispy carnitas, cover a baking sheet with foil. Turn the broiler on high. Spread the meat out on the baking sheet. Broil for 4-6 minutes until crispy. Toss with some of the cooking juice after broiling to add moisture back to the pork.