Rinse dried shiitake mushrooms under running water; Soak them in water for 3 hours; Remove and drain them; Discard the stems with a pair of kitchen scissors; Chop the remaining with a vegetable knife.
Rinse salted cabbage under running water; Soak it in water for 10 minutes; Remove and drain it; Chop it.
Rinse, drain, peel and chop ginger.
Rinse fat pork under running water; Pat-dry it with kitchen paper; Chop it.
Add seasoning (1) into a mixing bowl; Mix; Add the fat pork, the salted cabbage, the dried shiitake mushrooms and the ginger; Mix; Leave it for 40 minutes.
Hold a freshwater drum firmly by the head and scrape the scales from the tail towards the gills with a fish scaler; Rinse the fish under running water; Insert the knife into the anus near the tail; Draw the knife toward the head, splitting the fish to the base of the gills; Spread the abdominal cavity with fingers; Reach in and pull out the entrails; Rinse the cavity under running water; Cut off the head with the knife; Rinse the fish under running water again; Pat-dry the fish with kitchen paper; Rub seasoning (1) into the fish; Leave it for 30 minutes.
Rinse and drain coriander; Cut off any roots and most of the stems.
Fill a wok with water; Stack a bamboo steamer in the wok; Bring to the boil over a high heat.
Arrange the freshwater drum on a steaming plate; Evenly lay all other remaining ingredients (including the seasonings) on the fish; Arrange the steaming plate in the bamboo steamer; Steam over a high heat for 13 minutes; Turn off the heat; Garnish it with the coriander; Ready to serve.