Wash hands with soap and water.
Gently rub garlic and limes under cold running water.
Place garlic, lime juice, oil, salt, black pepper, oregano, onion powder, cumin, peppers and adobo sauce in a small food processor. Pulse until well combined and a paste is formed.
Rub the pork shoulder with the chipotle paste, rubbing in thoroughly on all sides. Do not rinse raw poultry or meat. Wash hands with soap and water after handling raw pork.
Gently rub orange under cold running water.
Place orange juice, chicken broth, bay leaves and seasoned pork shoulder into a slow cooker. Cook for 8 hours on low or 4hours on high, until internal temperature reaches 145° F on a food thermometer. The pork should be so tender that meat falls apart easily.
Remove pork from slow cooker and shred the meat using two forks, removing excess fat. Taste and adjust seasoning if needed.
Heat oven to broil. Line one baking sheet with foil and spray with cooking oil.
Place carnitas onto a baking sheet with half of the juices and broil until most of the pork looks golden, crisp and crusted, about 4 minutes. Remove from oven.
Gently rinse cilantro, pat dry and chop.
Garnish carnitas with chopped cilantro, if desired.