Place each chicken breast half between 2 sheets of heavy-duty plastic wrap; pound to 1/2-inch thickness using a meat mallet or rolling pin.
Combine bourbon and next 9 ingredients (bourbon through garlic). Reserve 1/3 cup marinade. Pour remaining marinade into a zip-top plastic bag; add chicken. Seal and marinate in refrigerator 1 hour, turning occasionally.
Preheat grill to medium-hot using both burners.
Turn left burner off (leave right burner on). Remove chicken from bag; discard marinade. Coat grill rack with cooking spray. Place chicken on grill rack over right burner; grill 2 minutes on each side or until browned. Move chicken to grill rack over left burner. Cover and cook 5 minutes or until done. Slice each breast diagonally into thin strips; place chicken on a platter. Cover loosely with foil.
Combine water and cornstarch, stirring well with a whisk. Place reserved 1/3 cup marinade in a small saucepan; stir in cornstarch mixture. Bring to a boil; cook 15 seconds, stirring constantly. Drizzle sauce over chicken; sprinkle with sesame seeds.