Toss the cubed chicken with the cornstarch until lightly coated.
In a small bowl, whisk together the honey, soy sauce, rice vinegar, ginger, and garlic to make the sauce.
Heat 1 tablespoon of oil in a large skillet or wok over medium-high heat. Cook the chicken for 5-6 minutes, until golden and cooked through. Transfer to a plate.
Add the remaining oil, then the bell pepper and broccoli. Stir-fry for 4-5 minutes, until crisp-tender.
Return the chicken to the pan and pour in the sauce. Cook for 2-3 minutes, stirring, until the sauce thickens and coats everything.
Serve over rice, topped with sesame seeds and green onion.