Cut chicken breasts into small bite size pieces. Heat oil over medium-high heat in a large heavy duty pan. Add the chicken breasts and taco seasoning to the pan. Sautee 4-5 minutes then add the bell pepper, onion, and garlic, sautee another 5 minutes or until the chicken is cooked through. Remove mixture from the pan and set aside.
To the same pan, add ½ teaspoon oil and a tortilla, top with a handful of shredded cheese, and 1/4th the chicken mixture, then with more cheese. Fold the tortilla and cook on both sides until crispy and golden. Remove from the pan and repeat with remaining tortillas.
To serve: Slice tortillas in half or thirds and serve with sour-cream, salsa, guacamole or your favorite dipping sauce.
Optional: Add a few slices of avocado into the tortilla before adding the 2nd handful of cheese.