Season chicken with salt and pepper. Mix with the cornstarch and coat pieces well. In a separate bowl, mix all of the ingredients for the sauce together.
Heat a skillet (or a wok if you have one) over high heat until it starts to smoke. Add the peanut oil and the garlic, and fry for a few seconds. Add the chicken and stir-fry for 2 minutes. As the chicken starts to turn opaque, add the dry sherry. Cook for another 2 minutes, then pour in the sauce and bring to a boil.
Once the chicken is cooked through and the sauce has reduced, add the scallions and cook for just under a minute. Serve over rice and enjoy!
*Recipe inspired by Ching-He Huang.