Heat a wok up over a high heat. Spray in a liberal amount of oil. Once hot, add in the egg. Stir it around in the wok well and allow to set slightly then break it up into pieces. Push to the side of the wok and spray in more oil. Add the whites of the onion, and the mushrooms. Add a pinch of salt and some red chilli flakes to taste. Add in the garlic and ginger. Toss everything together.