Begin to cook 4 servings of rice following the package directions.
In a lidded jar, combine all the sauce ingredients. Seal with the lid and shake vigorously.
Cut chicken breast into 1-inch pieces and season with salt and pepper on all sides. Set aside.
Stir-fry:
Heat a large nonstick pan over medium-high heat. Once hot, add 1 tablespoon of the oil. Add the chicken pieces to the pan and cook them for 5 to 7 minutes, flipping them halfway through. Once cooked, remove them from the pan onto a plate and set them aside.
Reduce the heat to medium and add the remaining 1 tablespoon of oil to the pan and once it is hot, add the broccoli florets. Cook, stirring occasionally, until the broccoli is tender, about 4 minutes. If using frozen broccoli florets, you can microwave them for the time listed on the bag, and add them to the pan hot with the chicken.
Return the chicken to the pan with the broccoli. Pour the sauce over the chicken and broccoli and stir to coat everything with the sauce. Bring the mixture to a boil, reduce the heat to low, and simmer it, stirring, for 1 minute or until the sauce thickens slightly.
Serve the chicken and broccoli with the cooked rice.
Notes
The sauce must come to a boil in order for the cornstarch to work as a thickening agent. Once it starts to boil, reduce the heat to a simmer. If you want more sauce, add up to ½ cup warm water to the pan and mix to combine.