Add the onion, peppers, garlic, and spices (cumin, oregano, chili powder, salt, and pepper – plus the beans if you’re using them) to the bottom of a slow cooker. Arrange the chicken on top of the vegetables in a single layer.
Turn the heat to HIGH. Add coconut milk, stir, and replace the lid. Continue heating the chili for an additional 10-15 minutes or until it’s heated through.
Stir in the lime juice and cilantro. Taste and adjust seasonings as desired. Ladle it into bowls garnished with chopped cilantro, avocado, and/or lime wedges, if desired.