In a small bowl, combine the 2 tablespoons soy sauce, 2 tablespoons Shaoxing rice wine, and 2 teaspoons sesame oil, and stir well.
☞ TESTER TIP: Once you begin cooking, this fish comes together very quickly. Have your sauce, tongs, and serving plate for the fish ready before you start cooking.
Fill the base of a steamer pan or a wok with about 4 inches (10 cm) of water. Place the steamer basket over the water.
Arrange the 3/4 pound halibut fillets, skin-side down, on a plate that will fit inside the steamer. (If you have more than 1 piece of fish, leave a little space between them.) Lightly season the fish with the 1/2 teaspoon table salt and then scatter the 2 tablespoons shredded or grated fresh ginger over the fish.
Place the plate in position inside the basket or on the rack, and bring the steaming water to a rolling boil over high heat.
When the steam a-flowing well, adjust the heat to maintain an even flow, and cover the steamer basket with its lid. Cook until the fish is opaque throughout when checked at the thickest part, 6 to 12 minutes, depending on the thickness of the fish. Turn off the heat and leave the fish in the steamer.
In a small pan or skillet over medium-high heat, warm the 2 tablespoons mild vegetable oil until hot and tiny wisps of smoke appear, about 1 minute.
Meanwhile, transfer the fish to a platter, leaving any liquid behind. Scatter the 3 tablespoons thinly sliced scallion over the fish.
Now, here’s the trick to that restaurant-quality finish: Drizzle the hot oil directly over the scallions and ginger. It'll sizzle and pop, instantly waking up all those gorgeous aromatics.
Pour the soy-wine sauce over the whole shebang and rush to the table.