In a medium bowl, whisk together chicken broth, fresh orange juice, and lime juice with the chili powder, smoked paprika, Mexican oregano, and ground cumin. Season with salt and black pepper, to taste, and set aside.
Push the “Sauté” button on Instant Pot. Once the display reads “On,” add 1 tablespoon olive oil and half the pork shoulder pieces to the container. Season with salt and black pepper, to taste, and cook until pork is browned on all sides, approximately 1-2 minutes per side.
Once browned, transfer seared pork to a plate and repeat this process with additional olive oil and the rest of pork. Remove browned pork from the Instant Pot and set aside.
Optional: Add remaining tablespoon olive oil to the container, along with red onion, jalapeno, and fresh garlic. Sauté, stirring occasionally, until soft and translucent, approximately 3-4 minutes.
Add browned pork back to the pot and pour chicken broth/orange juice mixture over top. Add lid and seal, making sure the steam release handle is positioned toward “Sealing.”
Press the “Manual” button and set the time to 30 minutes at high pressure. Once the cooking time is up, allow 20-25 minutes for the “natural release” of the steam inside the Instant Pot. After that time, perform a manual “quick release” to vent any remaining steam to release lid.
A few minutes before the steam is fully released, preheat oven broiler to high (if you choose to broil). Line a large, rimmed baking sheet with aluminum foil. Transfer pork to the prepared baking sheet and gently shred with two forks. Drizzle with ¼ cup juices from the Instant Pot and toss to combine before spreading into a thin, even layer.
Optional: Place pork under the broiler for 4-5 minutes, then remove from oven and add a little more juice before turning the meat to brown the other side. Place back under the broiler for another 4-5 minutes or until the pork is nice and crispy on the edges.
Once pork is under the broiler, press “Sauté” on the Instant Pot to reduce the cooking liquid by one half while the pork is broiling. If you aren’t broiling cover your meat in serving dish to keep warm while you reduce the liquid.
When finished broiling, remove baking sheet from oven and serve immediately with the reduced cooking liquid, fresh lime wedges, and chopped cilantro. Enjoy!