Preheat oven to 450 degrees F.
Line a sheet pan with foil, and spray with nonstick cooking spray.
Mix together garlic powder, chili powder, cumin, salt and pepper; set aside.
Slice green peppers and onions into thin slices.
Cut chicken breasts and steak into small slices, against the grain.
On the sheet pan, put the veggies on one side and the meat on the other.
Drizzle the entire pan with canola oil, making sure it is all evenly coated.
Sprinkle seasoning mixture evenly over the entire pan.
Cook for 10 to 20 minutes or until desired doneness. The thin slices of the meat and veggies will cook quickly. Check oven and stir once or twice.
Serve with tortillas, rice and your favorite condiments.