Combine all of the sauce ingredients and stir until corn starch is dissolved. Set aside.
In a wok or large, deep pan, heat 2 tbsp sesame oil on medium high heat.
Make sure pan is hot and sauté the chicken for 5-7 minutes until it is 95% done and then remove and set aside.
Make sure the pan is still hot and add the onion and garlic and sauté for another 1-2 minutes until onion is translucent.
Add the rest of the vegetables and sauté for another 3 minutes. Meanwhile, re-stir the sauce to make sure the cornstarch re-dissolves.
Add the chicken back to the pan as well as the sauce and stir until sauce thickens. Add most of the green onions and cilantro (leaving some for garnish) and let cook for another 3 minutes or so.
Sprinkle sesame seeds and cilantro and rest of green onion over the finished product and serve over rice.