Pour 1.5L of water into a steaming pot. Switch on the stove to high heat. Cover the pot and let it come to a rolling boil.
Marinate the fish with salt, distributing it evenly in the scores, stomach and on the other side of the fish.
Stuff half of the ginger strips in the stomach of the fish. Layer the other half on the steaming plate and place the fish on top of it.
Cut the roots from the cilantro stalks and stuff them in the fish's stomach.
Place the Chinese cabbage leaves under the fish.
Sprinkle the red chilli strips, tomato wedges, halved shiitake mushrooms and cut, cubed tofu over the fish. Place the steaming plate into the steamer and put it over the boiling water. Cover the pot and let it cook for 7 minutes.
Meanwhile, add 100ml of water into a mixing bowl. Smash the sour plums and add them all, with the brine, into the mixing bowl.
Add and stir in the oyster sauce and light soy sauce into the sour plum mixture.
Once the fish has been steaming for 7 minutes, pour all the sour plum mixture over the fish. Cover the pot again and continue steaming the fish for 5 minutes.
When 5 minutes is over, carefully remove the fish from the steaming pot with a steam clamp and/ or mittens.
Sprinkle the chopped cilantro leaves and crispy shallots over the fish. Serve with white rice.