Soak the dried fungus in boiling-hot water for 3–4 minutes or until soft, then drain. Remove and discard the hard stalks and roughly chop.
Heat the oil in a wok or large frying pan. Stir-fry the garlic over a medium heat for 1–2 minutes or until lightly browned. Add the pork and onion and stir-fry for 4–5 minutes or until the pork is cooked.
Add the water chestnuts, ginger, fungus, stock or water, fish sauce, oyster sauce and spring onions. Stir-fry for another 2–3 minutes. Taste and adjust the seasoning.
Spoon on to a warm serving plate, then sprinkle with ground white pepper, coriander and chilli slices.