Peel and cut the kohlrabi into thin strips. Grate the onion and ginger and cut the crab rolls into rings. In a Chinese wok, pour 2 tablespoons of oil. Once hot, place the onions and ginger in. Fry for a minute and add the kohlrabi, which you also fry for 1 minute.
Throw in the crab rolls for about half a minute, then remove the mixture from the wok and clean it with a napkin. Beat the eggs with 1 tablespoon of water, black pepper and salt. Add 1-2 tablespoons of oil to a wok, then add the well-beaten eggs, so as to obtain a thin pancake.
Periodically lift the pancake to allow the raw egg to distribute and fry evenly. On it, sprinkle the vegetables. You can fold it into two or leave it as is, then transfer it to a plate. For the sauce, pour in some hot water over the mushrooms so that they swell, then drain and julienne them.