Layer the diced onion and minced garlic at the base of the slow cooker vessel.
Season the chicken breasts with cumin, oregano, salt, and pepper.
Place the seasoned chicken into the slow cooker and pour the salsa verde over the top.
Seal the lid and cook on High for 4 hours or Low for 8 hours until internal temperature reaches 165 degrees Fahrenheit.
Extract the chicken and shred the muscle fibers using two forks.
Reincorporate the shredded chicken into the cooking liquid and stir in the lime juice.
Garnish with fresh cilantro before serving.