Using a sharp knife, trim the fat from the chicken, and slice it into strips.
In a small bowl, combine the soy sauce and sherry.
Add the chicken, and mix well.
Allow to marinate for at least an hour.
Add the egg to the chicken, and mix thoroughly.
Put the cornflour in a shallow dish, and dredge the chicken in it, a few pieces at a time, placing the dredged pieces on a wire cooling rack, making sure that they are not touching each other.
Allow the chicken to rest, untouched, for 30 minutes. Be sure to reserve the cornflour for later use.
Tip out the liquid from the bowl that you were using to marinate the chicken.
In that bowl, add the boiling water, chicken stock powder, and sugar.
Stir until the sugar has dissolved, then add the remaining sauce ingredients.
Set sauce aside for now.
Set oven to 50ºC (Keep warm temperature).
Dredge the chicken in the cornflour that you reserved from earlier. You may need to add some more cornflour to coat all of the chicken pieces.
Heat 3 tbsp oil in a wok, and add the chicken, shallow-frying for about 2 minutes, stirring constantly, until golden.
Remove from heat, and put chicken on a plate lined with paper towels, and place in the oven. (I also put the sliced carrot on a plate, and place that in the oven at this point - It helps to make the carrot a little bit more tender, so you don't have to cook it for as long, later).
Clean the wok, and add 1 tbsp of fresh oil.
Add the ginger and garlic to the oil, while it is heating.
Once the oil is hot, add the sauce, followed by all of the vegetables, and the noodles.
Stir fry for 1 - 2 minutes, then add the chicken.
Reduce heat, and stir through for a further minute.