Add onion, garlic and chicken broth to the bottom of a slow cooker.
Rinse the pork shoulder and pat dry. Rub with seasonings on all sides and place in slow cooker, fat side up.
Squeeze orange and lime over top of pork shoulder.
Slow cook on low for 5-6 hours or until the internal temperature reaches about 180-190 degrees (higher temp allows for collagen breakdown and makes it easy to pull apart). Remove pork from slow cooker and allow to rest for 5-10 minutes on a cutting board.
Pull the pork shoulder, removing any fat and remaining connective tissue. Arrange on a foil lined baking sheet and broil for 5 minutes, then remove and turn the pulled pork. Broil for another 5 minutes. Repeat the process additional times for extra crispy carnitas.
I used a 3.78 lb boneless pork shoulder and weighed it out to be 745 grams (~1 lb 10 oz) after cooking and removing any remaining fat. Each cut of pork shoulder will be slightly different and will impact the nutrition per serving.