Prepare the Marinade: In a bowl, combine the oregano, paprika, thyme, onion powder, mashed garlic, lime juice, vinegar, soy sauce, orange juice, salt, and pepper. Stir until all the ingredients are well blended.
Marinate the Pork: Place the pork shoulder chunks into the marinade and mix thoroughly. Ensure each piece is well-coated. If you have time, let the pork marinate for 30 minutes to an hour. For a more intense flavor, you can even marinate it overnight in the refrigerator.
Cook in the Instant Pot: Place the marinated pork in the Instant Pot along with the marinade juices. Cook until the pork is tender enough to shred with a fork. In most cases, this will take around 60-90 minutes. If you don’t have an Instant Pot, you can use a slow cooker or pressure cooker.
Natural Release: After the 30 minutes of cooking, allow the pressure to release naturally for about 10 minutes. Then, carefully release any remaining pressure by turning the valve to "Venting."
Shred the pork: Once the pork is fully cooked, it should easily fall apart when you pull it with a fork. You can fry it in a pan to crisp up the edges, but I often skip this step because I find the top of the pork gets nicely browned in the Instant Pot.
Shred the Pork: Once the pork is fully cooked and tender, remove it from the Instant Pot. Use two forks to shred the meat. If you want a crispy texture, transfer the shredded pork to a baking sheet and broil it in the oven for 5-7 minutes until the edges are crispy.
Serving: Serve the carnitas on whole wheat tortillas with slices of red bell peppers, avocado, and grilled peppers for extra flavor and texture. You can also serve them with your favorite toppings like salsa or cilantro.