Place the chicken in a large zip baggie and refrigerate.
Prepare the plum glaze: In a medium saucepan, combine the rice wine, soy sauce, plum sauce, water, vinegar, honey, salt and pepper. Bring to a boil over medium heat. Reduce heat to low and simmer until mixture reduces by about ⅓. Glaze should thicken slightly. Remove from heat and cool.
Add half of the plum glaze to the chicken in the bag, and marinate for at least a couple of hours or overnight (refrigerated).
Preheat the grill to medium heat and coat with oil or grill spray.
Remove chicken from the bag (then discard the bag and marinade) and grill 4 to 5 minutes on the first side, until good grill marks are showing. Flip and grill an additional 3 to 4 minutes, or until the chicken is cooked through.
Remove chicken to a platter and brush the reserved plum glaze on top.
Notes
If you are preparing this recipe as gluten-free, just be sure to use brands of soy sauce and plum sauce that are known to be GF.