Place the cleaned mussels in a wide pan with a little water.
Cover with a lid and boil hard until the shells have opened, shaking the pan occasionally.
Remove the mussels from their shells and reserve.
Discard mussels that have not opened.
Heat the oil in a wok.
Add the spring onions and stir-fry gently for a few seconds.
Add the stock, bean curd, mussels, straw mushrooms, Chinese cabbage, salt and pepper, simmer gently for 5 min.
Blend the cornflour with the water and stir it into the soup to thicken it slightly.