This is a super easy recipe. Throw the pork and spices in the crockpot and leave for the day. It shreds easily and then you put it into tortillas for dinner!
Toss the pork in the bowl of a slow cooker with salt, pepper, and oregano to coat. Place the onion pieces on top of the pork. Cover the slow cooker and cook the pork on a low setting until the meat is very tender and falling apart, about 6 hours (I've left it up to 10 hours, and it's been perfect either way).
Using a slotted spoon, transfer the pork to a cutting board. Discard the onion pieces. Using clean fingers (or two forks), shred the pork; transfer the carnitas to a platter. Place avocado slices, cilantro sprigs, and sliced red bell peppers, if desired, alongside.
Wrap corn or flour tortillas in a damp kitchen towel; microwave until warm, about 1 minute. Serve the carnitas with warm tortillas and green salsa.
Notes
If you need to prepare this recipe as GLUTEN FREE, just be sure to use a GF corn tortilla instead of flour.