Prep the base: Scatter sliced onion and minced garlic in the bottom of the slow cooker.
This creates a flavorful bed that prevents sticking and adds sweetness.
Season the chicken: Pat chicken dry and sprinkle with salt, pepper, cumin, chili powder, and oregano. Place the chicken on top of the onions.
Add liquids: Pour in salsa verde and chicken broth. If using, add a spoonful of canned green chiles for extra kick.
Cook low and slow: Cover and cook on Low for 4–6 hours or High for 2.5–3.5 hours, until the chicken is very tender and shreds easily with two forks.
Shred and brighten: Transfer chicken to a cutting board and shred.
Stir lime zest and juice into the sauce in the slow cooker, then return the chicken and toss to coat.
Finish with herbs: Stir in chopped cilantro. Taste and adjust salt, lime, and spice as needed.
Serve: Spoon into tortillas, over rice, or into bowls with your favorite toppings.