- Combine Kikkoman Gluten-Free Teriyaki Marinade & Sauce and sugar in measuring cup, stirring until sugar dissolves. Remove ½ cup of mixture and pour over chicken in large resealable storage bag. Press air out of bag and seal bag. Turn bag over several times to coat chicken well. Marinate for 15 minutes.
- Add enough water to remaining teriyaki sauce mixture to measure ⅔ cup; stir in cornstarch. Place in a small saucepan and cook, stirring frequently, for 1 minute, or until sauce boils and thickens slightly, adding an additional tablespoon of Kikkoman Gluten-Free Teriyaki Marinade & Sauce, if needed.
- Cook chicken on a well-oiled grill for 3 minutes on each side or until cooked through. Cover loosely with foil and let rest for 5-10 minutes.
- While chicken is resting, place vegetables in a grill basket, close the grill lid, and cook until crisp-tender, tossing occasionally, 5-10 minutes.
- Cut chicken into ½-inch slices and serve over rice in large individual serving bowls with vegetables on the side. Drizzle with sauce and garnish with green onions and sesame seeds.