Mixing all ingredients for fajita seasoning in a small bowl.
Then slice bell peppers and onions into 1/4-1/2 inch strips.
Add half of the canned diced tomatoes into the crockpot, and spread evenly at the bottom. Then add half of the sliced bell peppers and onions into the crockpot. Sprinkle 1/2 of the fajita seasoning on top.
Add Chicken breasts on top of the vegetables, and sprinkle another 1/2 of the fajita seasoning. Top with the rest of diced tomatoes.
Add the rest bell peppers and onions.
Seal the lid of the crockpot. Cook it on HIGH for 3-4 hours, or LOW for 6-8 hours. When it’s done, you can either cut the chicken into strips or shred it.
Spoon the chicken, onions and peppers into hot tortillas. Squeeze lime juice and garnish with optional cilantro, avocado and sour cream. Serve and enjoy!