Tie the spring onion in knots like a real Chinese chef! Put all the ingredients (except the rice wine) in a large saucepan and cover with cold water. Bring to the boil and skim off any scum. Reduce the heat, cover and simmer gently for approximately 4 hours, skimming regularly. Add the rice wine 5 minutes before the end of the cooking time. Strain the stock, cool, then refrigerate.