Grate ginger. Slice green onions at an angle and separate the green and white parts. Rough chop cilantro. Save some green onion and cilantro for garnish, and then set the rest aside.
Combine the light soy sauce, salt, sugar, and hot water in a small bowl, and mix until the sugar and salt are dissolved. Set aside.
Prepare your steaming set up in a wok by filling the wok with 1-2 inches of water. Bring to a boil. Place a metal steam basket in the wok.
Rinse fish and then season with salt and pepper. Carefully place it on the steamer basket, and adjust the heat to medium. The water should be at a slow boil and generates a good amount of steam.
Depending on the size and thickness of the fish, cover and steam for 7-10 minutes until cooked through. Turn off heat and set aside.
To make the sauce, heat a wok or small saucepan to medium high heat, and add vegetable oil. Add ginger, and fry for 1 minute. Add the white parts of the green onion and cook for 30 seconds.Then add rest of the green onion and cilantro. The mixture should be sizzling.
Add the soy sauce mixture. Bring the mixture to a simmer, and cook until the scallions and cilantro are just wilted, about 30 seconds. Pour mixture over fish. Garnish with green onions and cilantro.