Wash the chicken and cut it into small bite-sized pieces. Don't make them too chunky/big as they will take time to fry especially after being coated with the marinade that has egg in it. Pat dry with a kitchen towel/tissue.
In a bowl place all the ingredients mentioned under 'for the marinade' and whisk it together. Add the chicken pieces and mix well. Cover the bowl and refrigerate for 20-30 minutes
Heat the vegetable oil in a wok/deep kadai and when it begins to smoke slightly, add the chicken and stir-fry. Make sure that the wok has been heated very well or else instead of frying, the chicken will release water. If in doubt, cook the chicken in 2-3 batches. When the chicken has turned golden, remove on a plate
Drain off the extra oil from the oil and wipe clean. Put it back on the heat. It should be smoking hot.
Add the broken red chillies and dry roast them for a few seconds, then add the chopped ginger & garlic and dry roast them too. Toss in the oyster sauce and mix everything. Add the chicken stock and bring the mixture to a boil
Now add the dark soy sauce, chilli flakes and check seasoning. Return the fried chicken pieces to the wok and add the dissolved cornstarch paste in parts until you get the desired thickness. Add extra stock to adjust the thickness and quantity of the gravy.
Finish with the sesame oil, vinegar, sugar and wine if using. Turn off the heat
Garnish with the crushed peanuts and serve hot