Soak the dried fungus in boiling-hot water for 3–4 minutes until it is soft, then drain. Remove and discard the hard stalks.
Heat the oil in a wok or large frying pan and stir-fry the garlic over a medium heat until it is lightly browned.
Cut any large mushrooms in half and remove the hard stalks. Add the mushrooms, fungus, onion, stock, 2 tablespoons of oyster sauce and ginger and stir-fry for another 4–5 minutes. Taste and adjust the seasoning, using the rest of the oyster sauce if necessary.
Spoon on to a serving plate, garnish with coriander leaves and serve immediately.