Prepare a steamer with a lid over a wok or a large pot with at least 2 litres of boiling water.
Rub the rice wine and salt over the salmon fillets and lay them on the dish skin-side down. Top with the ginger slices.
Steam the fish for 15–20 minutes until cooked. Use a chopstick to poke through the flesh at the thickest point; if there’s resistance, steam for a little longer.
Once the fish is cooked, remove the sliced ginger and turn off the steamer but let it sit in the residual heat so the fish stays hot.
For the chilli sauce, place the oil, black bean and chilli bean paste in a wok or medium pan and cook over a high heat, constantly moving it around to prevent burning, until fragrant (about 1 minute).
Add the ginger and garlic and fry for another 1 minute.
Add in the water plus the cooking liquid from the steamed fillets (hold the fish in place with chopsticks and tilt the juices from the dish into the wok or pan).
Add in the soy sauce, sugar and black vinegar. Bring to a simmer for 1 minute and taste. Add salt if required.
Reduce the heat to medium. Slowly stir in as much of the slurry as needed to reach your desired consistency – it should resemble a thick pouring gravy.
Turn off the heat. Pour the sauce over the top of the fish. Garnish with coriander, if desired.
