Preheat your oven to 400°F (200°C).
Slice chicken breasts into strips and place them in a bowl.
Chop bell peppers and onion into thin slices.
Add olive oil, chili powder, cumin, garlic powder, salt, and pepper to the chicken.
Toss the chicken to coat evenly with the spices.
Spread the chicken and vegetables evenly on a sheet pan.
Bake in the preheated oven for 25 minutes or until the chicken is cooked through.
Stir halfway through cooking for even roasting.
Once done, remove from the oven and let it rest for a few minutes.
Serve with tortillas and your favorite toppings.