Preheat oven to 425 degrees F (220 degrees C).Advertisement
Mix cornstarch, chili powder, paprika, sugar, salt, onion powder, garlic powder, and cumin together in a bowl.
Combine chicken, red bell peppers, and onion in a bowl; add cornstarch mixture and stir until evenly coated. Transfer to a baking dish.
Bake in the preheated oven until chicken is cooked through, about 30 minutes. Serve chicken mixture in corn tortillas.