Blanch the pioppino mushrooms, black fungus and straw mushrooms in boiling water for 3 minutes. Drain well and set aside.
Bring water to the boil. Cook the tofu for 5 minutes, drain and set aside.
In a small bowl, mix together the oyster sauce, sesame oil, salt, sugar and water. Set aside.
Heat a large frying pan with oil over high heat. Stir fry the garlic, spring onions and chilli until fragrant; about 2-3 minutes.
Stir in the onion and salt then cook until soft; 3-4 minutes.
Add the pioppino mushrooms, black fungus, straw mushrooms, tofu and sauce then stir to mix.
Heat through and drain off any liquid. Re-heat the mixture 1-2 minutes before serving.
Pioppino are a type of Japanese mushroom. They are also known as black poplar mushrooms and shimeji. Black fungus are also known as wood ear mushrooms. You will find both types of mushrooms in Asian speciality shops.
If you like a thicker sauce add a little bit of cornflour and water to the sauce towards the end.