Scrub the mussels thoroughly under cold running water. Pull off the hairy 'beards' and rinse again. Gently tap any open mussels and discard any that don't close.
Heat the oil in a wok over a medium heat. Add the garlic and fry until crisp and golden. Now stir in the black bean sauce, ginger, rice wine and soy sauce. Pour in the water and boil for 1 minute.
Throw in the mussels, cover and simmer over a medium heat for 3–4 minutes, until all the mussels have opened, discarding any that remain closed. Stir in the coriander and serve immediately.