In a blender, combine onion, garlic, pineapple, chipotle peppers, chili powder, cumin, oregano, salt, pepper, vinegar, and orange juice. Blend until smooth.
Set Instant Pot to sauté mode and heat vegetable oil. Add pork slices and brown on all sides.
Pour the blended marinade over the pork in the Instant Pot.
Close the lid, set to high pressure for 25 minutes.
Once done, do a quick release and shred the pork using two forks.
Serve the Al Pastor pork in tacos, burritos, or over rice.
Notes:
This recipe is a quick and easy way to enjoy the flavors of traditional Al Pastor without the need for a spit or grill.