In a bowl add the cornstarch and water. Mix until combined. Set aside.
In a sauté pan add the olive oil over medium heat. Allow the oil to get hot, which will take 2-3 minutes.
Add the chicken, salt, and pepper. Cook for 4-7 minutes or until the juices run clear. Transfer the chicken to a bowl. Set aside
Add the broccoli, carrots, peppers, and onions to the sauté pan. Sauté for 4-5 minutes until heated through the vegetables are still crisp. Transfer the vegetables to a bowl. Set aside.
To the sauté pan add the broth, soy sauce, honey, sesame seed oil, ginger, rice vinegar, garlic, and red pepper flakes. Mix until combined.
Add the cornstarch slurry to the sauté pan. Mix until combined. Stir for 2 to 3 minutes or until the sauce is thick.
Add the chicken and vegetables to the sauté pan. Toss until everything is coated in the sauce.
Sprinkle with sesame seeds and green onions if desired. Serve immediately with rice, optional.