Cut up and cube your chicken breasts and place chicken into a zip-top freezer bag or large bowl.
In a small bowl or mason jar, mix together soy sauce, rice wine vinegar, sesame oil, brown sugar, ginger, garlic, and red pepper flakes.
Pour HALF of the sauce over chicken and toss the chicken to coat evenly. Set aside to marinate while you prepare the vegetables and preheat the oven.
Preheat oven to 425 degrees. Prepare a rimmed baking sheet with aluminum foil (for easier cleanup) spritzed with non-stick cooking spray.
Remove chicken from marinade and place on baking sheet, spacing evenly.
Add vegetables around the chicken. Pour remaining sauce over the chicken and vegetables and sprinkle with toasted sesame seeds.
Bake for 15 minutes, turning chicken and vegetables halfway, or until chicken is cooked through.