Place half of the sliced peppers and onion in the slow cooker. Layer the chicken and coat with honey, olive oil, lime juice, all the seasonings and chopped tomatoes.
Lastly, add the remaining peppers and onions and cook for 4 hours on high.
Remove the chicken and shred it with a fork, then return it in in the slow-cooker. Mix well and cook for another 10 mins. on low.
Assemble fajitas and enjoy.
Suggested serving (not included in nutrition info): tortillas, sour cream, guacamole, coriander