Prepare rice as directed on the box.
In a medium bowl, make sauce by whisking together soy sauce, brown sugar, and cornstarch until smooth. Add ginger, garlic, and red pepper flakes and mix to combine. Reserve ⅓ of the marinade before adding the chicken and stir to coat. Refrigerate for 30 minutes.
In a large skillet or wok, over medium-high heat, add 1 tablespoon sesame oil. Add broccoli, carrots, and peppers and cook for about 5 minutes, or until just tender. Remove veggies to a dish and set aside.
Add remaining sesame oil in the skillet, and over medium-high heat, add chicken (minus the marinade) and cook for about 5 minutes, or until browned.
Add veggies and the reserved marinade, bringing to a boil. Cook for an additional 5 to 7 minutes or until chicken is cooked through and veggies are tender.
Serve over rice or noodles.
