Put the noodles in a large bowl and pour boiling water over them so that they are covered. Let soak for 10 minutes or according to the instructions on the package. Then drain thoroughly.
Heat sunflower oil in a large wok. Put the red onions and garlic in the wok and stir-fry for 2-3 minutes. Add the mushrooms and stir for about 5 minutes until cooked. Put the Chinese cabbage or pak choi, noodles, sherry and soy sauce in the wok. Mix all ingredients and stir-fry for 2-3 minutes until the liquid boils.
Place pasta with mushrooms in preheated bowls and sprinkle with spring onions and roasted sesame seeds.