Preparing the Carnitas: Preheat oven to 300°F (150°C). Season pork chunks with salt, pepper, cumin, chili powder, smoked paprika, and cayenne. In a large oven-safe pot or Dutch oven, heat olive oil over medium-high heat. Sear pork in batches until browned on all sides, about 2–3 minutes per side. Add orange juice, lime juice, orange peel, onion, and garlic. Cover with a lid and place in the oven. Slow-cook for 2–2.5 hours until pork is tender and easily shredded with a fork.