Prepare sauce. First, dilute cornstarch in water then in a small bowl, combine soy sauce, brown sugar, sesame oil, Shaoxing rice wine, ground black pepper, cornstarch and water mixture and chicken broth. Set aside.
Make the chicken marinade. Dilute cornstarch in water then in a large bowl combine brown sugar, soy sauce, sesame oil and cornstarch and water mixture. Add thinly sliced chicken breast and coat with marinade. Cover bowl with saran wrap and refrigerate for at least 30 minutes or longer, the longer the better.
In a smoking hot wok over medium heat, add oil and stir fry chicken breast quickly until fully cooked. Remove chicken from wok, leaving oil in wok. Set aside.
On the same wok with remaining oil, saute garlic until golden then stir-in fresh ginger and continue cooking for another 30 seconds. Note: I did not have fresh ginger instead I added ginger powder when I added the sauce. Toss-in green beans and cook for a minute then add water.
Bring to a simmer, cover wok and continue cooking until green beans are half cooked or so.
Stir-in sauce, raise heat to medium-high and continue stirring for about 90 minutes to 2 minutes until sauce is quite thick. Note: Add another teaspoon of cornstarch and water mixture, if sauce consistency is still not thick.
Toss-in chicken breast and continue cooking for a minute. Salt and pepper to taste. Note: Before adding salt, taste the sauce, it can be salty already due to soy sauce.
Turn off heat, add julienne white onion. Serve hot with white rice.
Notes
When you double the recipe, don’t overcrowd chicken breast when stir frying. Do it in batches so wok keeps it temperature hot. If you add too much chicken breast, it will release liquid and steam. You want it to fry not steam.
Also, wok should be smoking hot before adding oil.
If you prefer saucy, you can always double the sauce recipe.