Cut the meat into small cubes. Put the flour in a bowl, add the light soya sauce and ground ginger and stir to mix them well. Coat the meat with the mixture and let it stand like that for at least 30 minutes. Clean and cut the mushrooms into slices.
Peel the garlic and ginger and cut them into very thin slices. You can use them sliced this way or cut them into thin strips. Heat oil in a wok or frying pan, divide the meat into 2 parts and fry each separately.
Turn the cuts of meat from time to time. Fry each one for about 5 min. The flour from the meat will remain in the pan, but do not remove it because later you can use it to thicken the sauce. Remove most of the oil from the pan, leaving in only 2 tablespoons and warm them up again. Fry the garlic, ginger and mushrooms in it, stirring constantly, for 1 minute.