1Cut the scallions into 2-inch lengths, cut them in half lengthwise, and julienne. Thinly slice and julienne the ginger. Roughly chop the cilantro. Reserve 1/3 of the aromatics for later.
2Combine the light soy sauce, salt, sugar, and hot water in a small bowl until dissolved.
3Prepare a steaming setup with 1-2 inches of water and bring to a boil.
4Rinse the fish fillet and place it on an oblong heat-proof plate. Place the plate in the steamer and steam over medium heat for 7-10 minutes. Check for doneness by piercing the thickest part with a butter knife; it should pass through easily.
5Drain any liquid from the plate. Spread 1/3 of the raw aromatics over the fish.
6Heat 2 tablespoons vegetable oil in a wok or saucepan over medium-high heat. Fry the remaining 2/3 ginger for 1 minute, add the white parts of the scallions for 30 seconds, then add the rest of the scallions and cilantro.
7Add the soy sauce mixture to the wok, bring to a bubble, and cook until the aromatics are just wilted, about 30 seconds.
8Pour the mixture over the fish and serve immediately.
Increase all sauce and aromatic ingredients by 50% or double for larger fish fillets.
Some aromatics are cooked in the sauce while others are kept raw for a mix of textures and flavors.
You can place the raw aromatics on the fish after adding the sauce and then pour an extra tablespoon of hot vegetable oil over them for extra presentation and sizzle.
Use a dull butter knife to check doneness; the fish is done when the knife falls through without resistance.