Shell and skin chestnuts, then deep-fry in hot oil for less than a minute. Put the prefried chestnuts in a small pot of water and cook until done.
Remove and leave aside.
Marinate chicken with seasoning (A) for at least an hour. Deep-fry the chicken pieces in hot oil for a while. Dish out and put aside.
Leave 1-2 tablespoons oil in a wok and fry ginger and garlic until fragrant. Add a dash of Shao Hsing wine, if using.
Add chicken and pour in combined sauce (B). Bring to a boil, then reduce the heat and braise for 20 minutes until sauce is reduced. Add chestnuts and continue to simmer for 10 minutes more. Put in spring onion then dish out and serve.