Dice chicken, onion, and bell pepper and place in bowl. Add Teriyaki marinade and refrigerate for at least 30 minutes.
Heat large non stick skillet over medium high heat, add two tbls. vegetable oil. Place chicken mixture in heated skillet stirring occasionally. Turn heat down to med and continue to cook until chicken is done and veggies are at the desired consistency.
Warm flour tortillas in microwave for approx 10 seconds each (to make them easier to handle). Fill tortillas with chicken mixture and top with ranch dressing. ENJOY!!!!