Preheat oven to 425°F. Toss chicken with cornstarch, garlic powder, and sesame oil. Spread on one side of a sheet pan. Place broccoli and bell peppers on the other side and drizzle lightly with oil.
Bake for 10 minutes. Meanwhile, whisk together all sauce ingredients.
Remove sheet pan from oven and pour sauce over chicken and the veggies. Toss to coat. Return to oven and bake for 8-10 more minutes, until chicken is cooked through and sauce has thickened.
Serve with rice, quinoa, any grain you prefer.
Notes
Store leftovers in an airtight container in the refrigerator for up to 4 days. The flavors continue to develop, making this a great meal prep option for lunches.