In large bowl, mix together onion powder, chili powder, garlic salt, paprika, sugar, cupin, crushed red pepper, and cayenne pepper
Add chicken slices, and mix
Set aside
Over a medium heat, warm cast iron skillet
Add 1 Tbsp oil, once warmed then add onion and bell peppers. Saute 10 minutes
When tender, remove from skillet and set aside
Add remaining oil and cook chicken until no longer pink. Approximately 7 minutes
Stir in bell pepper mix
Simmer approximately 3 minutes
Serve with warmed tortillas and top with shredded fiesta-style cheese blend