Set the 6-quart Instant Pot to the Meat setting.
In a large bowl, combine the garlic, pork, oregano, cumin, chili powder, salt, zest, pepper, and oil, mixing well.
Transfer the mixture to the Instant Pot.
Secure the lid on the Instant Pot and seal the vent.
Pressure cook on high for 35 minutes.
Once done, perform a quick release of the pressure and let the pork stand for 15 minutes.
Remove the lid and use two forks to shred the pork.
Preheat the broiler to high.
Transfer the shredded pork to a rimmed baking pan and broil for 5 minutes, or until it becomes crisp and browned.
Serve the carnitas in tortillas with your choice of toppings, if desired.
