Repeatedly boil chicken in soy sauce water is to prevent overcooking. It is the trick that makes chicken meat reach the highest tender level.
You can add other seasonings in the boiling water if you desire. Such as the five-spice powder, white pepper and ginger slices.
Rinsing in the cold water makes chicken skin tight and tender. Using ice water can achieve better results. Try it then you will know.
Instead of soy sauce, You can use dark soy sauce, barbecue sauce, and even honey sauce. Trying to add creativity seasoning on traditional Chinese chicken recipe is the spirit of Chinese cuisine.