In a bowl, mix together salt, black pepper, cumin, oregano, and cayenne pepper. Rub the spice mixture all over the pork chunks.

Place the pork in the slow cooker.

Add chopped onion, minced garlic, orange juice, and chicken broth to the slow cooker.

Cover and cook on low for 6-8 hours or until the pork is tender and easily shredded.

Remove the pork from the slow cooker and shred it using two forks.

Optional: Heat a skillet over medium-high heat and add the shredded pork to crisp it up.

Serve the carnitas in warm corn tortillas, topped with chopped cilantro and lime wedges.