Rinse spring onion; Cut off any roots; Julienne the remaining.
Rinse, drain, peel and julienne ginger.
Place 1 salted lemon in a ceramic mortar; Mash it with a pestle; Stir seasonings into the mashed salted lemon.
Cut 1 salted lemon into cubes.
Hold a fish 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, and 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 the fish with the mixture from the step 3 and stuff the cavity of the fish with the mixture; Leave it for 20 minutes.
Fill a wok with water; Stack a bamboo steamer in the wok; Bring to the boil over a high heat.
Arrange the fish from the step 6 on a steaming plate; Lay the salted lemon cubes and the ginger juliennes over the fish; Spread 2/3 spring onion juliennes on the top; Arrange the steaming plate in a bamboo steamer; Steam over a high heat for 8 minutes; Turn to a low heat; Lay the remaining spring onion juliennes on the fish; Steam over a high heat for 1 more minute; Turn off the heat; Arrange it on a serving plate; Ready to serve.