Slice chicken into small strips. In a large bowl mix garlic powder, seasoning salt, cumin, chili powder, red pepper flakes, 2 tablespoons vegetable oil and lemon juice.
Add chicken strips and toss to coat. Cover and marinate in the refrigerator for 2 hours.
In a skillet add 2 tablespoons of oil and sauté onions and green peppers for 3 minutes or until the vegetables have reached your desired tenderness.
Remove from pan and set aside.
Add more oil to the pan if necessary. Add chicken strips and sauté until no longer pink inside (fully cooked).
Add vegetables back to the pan and toss with the chicken. Spoon mixture onto flour tortillas; add optional condiments (if you want) and serve.