2. Place the chicken and teriyaki marinade in a plastic bag and seal tight. Let the chicken marinate for at least 30 minutes, or overnight.
3. Preheat the grill to medium-high.
4. Grill the chicken on each side until it is cooked through, about 4 to 6 minutes per side. Transfer the chicken to a cutting board to cool and then cut into small pieces.
For the wraps:
5. In a small bowl, combine the cream cheese and onion. Add salt and pepper to taste.
6. Lay the flour tortillas out on a work surface in front of you. Divide the cream cheese mixture among the tortillas, spreading it out in the center of each tortilla. Divide the chicken among the tortillas and then add the lettuce. Tightly roll each tortilla into a cylinder, ending with the seam side down.
7. Cut each wrap on the diagonal and serve.