In a small bowl or measuring cup, whisk together soy sauce, brown sugar, vinegar, oil, ginger, garlic, cornstarch and water. Add chili paste if using. Set aside.
In a large skillet, heat up olive oil. Add chicken and cook until no longer pink, done and starts to have golden brown color. Remove onto a plate. Set aside.
Add 2 teaspoons more of oil to the skillet. Add onion and pepper. Saute until the pepper is tender.
Add chicken back to skillet. Add sauce mixture and cook, stirring often until the sauce has thickened. Add steamed broccoli.
Serve over rice, garnished with sesame seeds and/or chopped green onions.
Notes
I highly recommend using steamable vegetables for this recipe. Steam broccoli and add to stir fry just before serving. If you add it with onion and pepper and then saute the vegetables together, the broccoli will loose it's vibrant green color and add too much water to the sauce. You can buy frozen bags of broccoli florets in the freezer section of any grocery store. Use my recipe to make the Perfect Fluffy Rice to serve with this Teriyaki Chicken Stir Fry. Over the years, I've got a wonderful feedback from those who made it to serve with my Asian takeout recipes. It's fail-proof and you do not need rice steamer to make it.