Rinse and drain coriander; Cut off any roots; Cut it into sections.
Discard any seeds of a salted lemon; Chop it.
Rinse and drain a lemon; Bisect it lengthwise with a vegetable knife; Slice it; Discard any seeds.
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; 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.
Fill a wok with water; Stack a bamboo steamer in the wok; Bring to the boil over a high heat.
Arrange most of the coriander on a steaming plate; Lay an half of the lemon slices on the coriander; Place the flathead mullet on the lemon; Evenly spread the salted lemon on the flathead mullet; Put the remaining fresh lemon slices on the top; Arrange the steaming plate in the bamboo steamer; Steam over a high heat for 10 minutes; Turn off the heat.
Add 1.5 tbsp oil into a pan; Bring to the boil over a high heat; Turn off the heat; Immediately drizzle it over the flathead mullet; Garnish it with the remaining coriander; Ready to serve.