Cook the rice according to package directions.
Meanwhile, heat 2 tablespoon of olive oil in 2 skillets.
In one skillet, add the chicken. In the other skillet, add the broccoli and bell pepper.
Cook the chicken and veggies until the chicken is browned and cooked through and the vegetables are softened, about 7-10 minutes.
Meanwhile, make the teriyaki sauce.
In a small bowl, whisk together the soy sauce, water, brown sugar, rice vinegar, sesame oil, garlic, and ginger. In a separate small bowl, whisk together 2 tablespoon of water with the cornstarch and then add it to the rest of the sauce. This ensures there are no clumps of cornstarch.
Add ½ cup of the sauce to the chicken and the rest to the vegetables, cooking another 1-2 minutes until the sauce has thickened.
Add rice, chicken, and vegetables to bowls and then top with sesame seeds and diced green onions.
Enjoy!