In a cup mix 3 tablespoons ice cold water and cornstarch making sure its thoroughly incorporated, then set aside.
In a medium sized bowl add brown sugar, dry sherry cooking wine, garlic, ginger, soy sauce and 1 tablespoon toasted sesame oil then stir. (You can also put all ingredients in a blender after mincing).
Next, slice chicken breast into thin 2-inch strips then place it into bowl with marinade. Cover and place in refrigerator for at least 30 minutes.
Place frying pan over medium heat, add ¼ cup water and broccoli, cover pan. Allow broccoli florets to steam for 2 minutes. Keep an eye on the broccoli as the water evaporated pretty quickly. Remove broccoli from pan and set aside in a bowl.
Next, make sure all water is removed from pan. Add remaining toasted sesame oil to pan and allow to heat for 1 minute. Add chicken without the marinade to pan and sauté for 3 minutes.
Add reserved cornstarch mixture into leftover marinade, mix well.
Then add marinade and broccoli in with chicken, sauté for another 2 minutes. Sauce will slightly thicken. Serve over rice and enjoy the tangy savory flavors.