Take the chicken breast and lightly grill for about 2 minutes until only the surface is white and cooked.
Combine soy sauce, rice wine and vinegar, sugar, and chicken boullion.
Take a fork and poke holes in the chicken on both sides.
Put the chicken in the marinade and marinade for about 40 minutes or until the chicken turns a medium dark reddish brown.
Remove the chicken from the marinade.
Combine the rest of the marinade with the cornstarch.
Before grilling heat the marinade on a stove or microwave until it thickens to about as thick as barbecue sauce, stirring constantly.
Grill chicken over VERY LOW heat (if you are using a charcoal grill, put the chicken to the side of the charcoal, not over it) until done (about 20-25 minutes for each inch of thickness; However, grill temperatures vary so you might have to cook for more or less time for the chicken to be done), sprinkling garlic and ginger on the meat to let the flavors sink into the chicken; The low heat lets the flavors sink into the meat; If the heat is too high, there won't be as much flavor as slow grilling has.
Brush or spoon the sauce onto the chicken as it is cooking about every 5 minutes or depending on your taste.
If you like, you can serve the chicken with the sauce.