In a large bowl soak the shitake mushrooms in hot water - this should take around 20 minutes. Drain, remove stalks and slice into bite size pieces.
Heat a large saucepan of water. Once boiling carefully add the chicken and boil for 12 minutes. As the chicken is cooking skim off the foam and fat.
Transfer the chicken to a large pan that can be sealed with a lid and pour over the cooking water just high enough to cover the meat. Add ginger, star anise and rice wine and bring to the boil. Turn down to low and simmer (uncovered) for a further 20 minutes. Now you can add the whites of the spring onion, shitake mushrooms, light soy sauce, dark soy sauce, sugar and a pinch of salt. Mix ingredients together, cover and simmer on a low heat for 30 minutes. Every 10 minutes give the chicken a stir as you do not want the pieces on the bottom to burn (you can also add more boiling water if the stew is looking dry). After 30 minutes, remove the lid and bring the liquid back up to the boil. If you have a lot of cooking liquid, reduce over a high heat for 5 minutes but remember to keep moving the chicken on the base of the pan. Add the corn flour mixture, stir thoroughly to thicken the gravy and then transfer to a serving plate.