Maple Syrup Korean Teriyaki Chicken

1/4 cup soy sauce
1 cup water
1/3 cup maple syrup
3 tablespoons dark sesame oil
2 garlic cloves, crushed
1 tablespoon gingerroot, minced
2 teaspoons black pepper, ground
5 boneless skinless chicken breast halves
3 cups brown rice, steamed
2 tablespoons cornstarch

Mix the soy sauce, 1 cup water, maple syrup, sesame oil, garlic, ginger, and pepper in a large resealable plastic bag. Set aside 1/3 cup of the mixture. Place the chicken in the bag, seal, and marinate at least 2 hours in the refrigerator.
Preheat the oven broiler. Lightly grease a baking dish.
Pour marinade from the bag into a saucepan, and bring to a boil. Mix in the cornstarch, and cook and stir until thickened.
Place chicken in the prepared baking dish. Basting frequently with the reserved 1/3 cup marinade, broil 8 minutes per side, until juices run clear. Place chicken over the cooked rice, and top with boiled marinade.