Cover fungus with boiling water in a bowl and leave to stand for 1 hour. Chop roughly.
Pour boiling water over noodles and soak for 3 to 4 minutes. Drain and cut into roughly 15 cm (6 in) lengths.
Heat oil in a hot wok and fry onion for a few minutes until it starts to brown. Add garlic and cook for another 30 seconds.
Add prawns and fungus and stir through just until pr