Preheat oven to 400°. Start off by chopping all of the bell peppers into slices (about 1″ by 1″) and place into glass baking container. (9″ by 12″ works best) Then slice onion into rings and then slice rings in half and separate. Add onions to peppers.
Take 1/4 cup of olive oil and add it to medium sauté pan. Add chicken breasts and saute until most of the pink is gone (do not fully cook chicken as it will finish cooking while you bake it).
Remove chicken from pan and dice. It will still be pink in the middle and that is okay! Add chicken to glass baking container with bell peppers and onions. Add remaining 3/4 cup of olive oil and spices and mix everything together.
Place baking container into oven and bake for 25 minutes.
Let cool for 5-10 minutes.
Serve on 2 corn tortillas. About 1/2 cup per tortilla. Enjoy!