Using paper towels, pat the fish thoroughly dry. Wrap the fish in fresh paper towels while you prepare the rest of the ingredients. The goal is to make the fish as dry as absolutely possible. Use a sharp knife to score both sides of the fish three times.
Once the prep work is done, unwrap the fish and dust it with a thin, even layer of cornstarch on both sides. This step will help keep the skin in tact during pan-frying.
Heat the wok until it starts to smoke, and immediately add the oil and ginger slices. Reduce the heat to medium. Once the ginger slices start to brown, remove them from the wok and set aside. Carefully lay the fish in the wok, and DO EVERYTHING IN YOUR POWER NOT TO MOVE OR TOUCH THE FISH for the next 5 minutes. You can tilt the wok around so the oil glides around to evenly brown the fish.
After 5 minutes, shake the wok slightly to see if the fish has seared enough to stop sticking to the wok. This is when you can carefully flip the fish over and do the same process for the other side.
Once both sides are nicely browned, add the ginger back to the wok along with the scallions, shaoxing wine, sugar, vinegar, dark soy sauce and light soy sauce. Keep the heat at medium low, and cook the fish by continuously spooning the cooking liquid over the fish. Cook on each side for 4-5 minutes. By now, the sauce should be cooked down and almost syrupy. Serve!
Tip: If you want to make sure the fish is done, carefully pick apart the thickest part of the fish. If the meat readily comes apart from the bone, it’s done. You can plate it so that the hole you made is facing down!