1. Toss pork into bowl of slow cooker with salt, black pepper, and dried oregano to coat. Place onion pieces on top of pork.

2. Cover slow cooker and cook pork on low setting until meat is very tender and falling apart, about 6 hours.

3. Using slotted spoon, transfer pork to cutting board. Discard onion pieces. Using fingers or fork, shred pork; transfer carnitas to platter.

4. Place avacado slices, cilantro, and sliced red bell peppers alongside.

5. Wrap corn tortillas in damp kitchen towel and microwave until warm about 1 minute.

6. Serve with warm tortillas and tomatillo salsa