Trim the extra fat off the pork roast and cut it into large 2-inch chunks. Turn the Instant Poton Sauté. Sprinkle the pork chunks with the ancho chile powder, cumin, oregano, 1 teaspoon salt, and 1/2 teaspoon pepper. Toss to coat. Add half the pork to the Instant Pot and brown on all sides. (The pork will pull away from the bottom of the pot when it's caramelized. No need to add oil.) Then transfer the pork to a plate and repeat with the remaining pork.
Take all of the pork chunks out of the pot. Sauté the onions and garlic for 2 minutes to soften. Then add the pork, orange juice, Old El Paso Chopped Green Chiles, and liquid smoke to the pot. Stir well.
Lock the lid into place. Set the Instant Pot on the Meat setting. Pressure cook for 30 minutes.
Once the timer goes off, turn off the Instant Pot and perform a Quick Release. When the steam valve button drops, it is safe to open the pot. Use tongs to shred the meat.
You can serve the carnitas as-is on Old El Paso Flour Tortillas. For crispy restaurant-style carnitas, scoop the shredded pork out of the pot with a slotted spoon, and spread in a thin layer on a baking sheet. Broil the carnitas for approximately 5 minutes to form crispy edges. Then serve on tortillas or as a topping for salads and nachos.
Don't have an Instant Pot? You can make this recipe in your slow cooker. Get the instructions here.