Prepare Marinade Mix as directed on package. Place chicken in large resealable plastic bag or glass dish. Add 1/2 of the marinade; turn to coat well. Reserve remaining marinade for brushing. Refrigerate chicken 15 minutes or longer for extra flavor. Remove chicken from marinade. Discard remaining marinade.
Grill chicken over medium heat 5 to 7 minutes per side or until cooked through. Grill onion slices 2 to 4 minutes per side or until tender-crisp. Brush chicken and onions with reserved marinade. Cut chicken into bite-size cubes. Separate onions into rings.
Stretch or roll dough on floured baking sheet to a 12- to 14-inch round, about 1/4-inch thick. Brush top of dough with oil. Place oiled-side down on the grill. Close lid. Grill over medium heat 1 to 2 minutes or until grill marks appear on the bottom of the crust. Carefully flip crust over using tongs or spatula.
Layer crust with 1/2 of the cheese, grilled chicken, onions and remaining cheese. Close lid. Grill 3 to 4 minutes longer or until cheese is melted and crust is browned. (Check pizza often to avoid burning. Rotate pizza, if necessary.) Slide pizza onto baking sheet. Sprinkle with cilantro, if desired. Slice and serve immediately.