Preheat oven to 350 degrees F.
To make the marinade: Add teriyaki sauce, oil, honey, ginger, garlic powder, red pepper flakes, and salt/pepper to taste to a small bowl. Whisk until all ingredients are combined and set aside.
In a large bowl, add in chicken, broccoli, bell peppers, and HALF of the marinade (reserving the rest for later) and toss until evenly coated. Let sit for about 10 minutes.
Spread chicken and veggies on a baking sheet, sprayed with cooking spray. Bake in the oven for about 20-25 minutes, tossing halfway through, and continue cooking until veggies are tender and chicken is cooked through.
Drizzle remaining marinade over top and sprinkle with sesame seeds. Enjoy as is, or serve over rice or quinoa!