Gather the ingredients.
In a resealable plastic bag, combine chile powder with salt, cumin, onion powder, garlic powder, cornstarch, water, and 2 tablespoons of the oil. Add chicken, bell pepper, and onion. Seal bag and knead gently to coat. Refrigerate for 15 minutes.
Heat the remaining 2 tablespoons of oil in a large cast iron skillet until shimmering. Empty the contents of the bag into the skillet and cook over high heat, stirring occasionally, until vegetables are crisp-tender and chicken is cooked through, about 8 minutes. Remove from heat and stir in lime juice.
Transfer chicken and vegetables to a large bowl and serve with warmed tortillas, lettuce, cheese, salsa, sour cream, and lime wedges.
