Boil base sauce ingredients in a pot over low to medium flame until sugar dissolves. Adjust to taste.
Marinate chicken in dark soya, light soya, sesame oil, Chinese cooking wine, cornstarch & sugar for one hour. (See Recipe notes 1)
Transfer marinated chicken into base sauce in the pot. Make sure you pour the marinade into the sauce as well. Bring to the boil. (See Recipe notes 2)Cover and turn off stove. Let pot sit covered for an hour to allow the chicken to cook through.
Boil the leftover sauce and let cool. Bottle and freeze for next time.
Notes
The marinade ingredients should be able to lightly cover the whole chicken.
The sauce is on the sweet side, so at this point, you should taste for seasoning and add a pinch of salt if you like.
The recipe produces enough sauce to cover a whole chicken. You can adjust accordingly. Also, the sauce can be reused, and usually tastes better with age!