1. Draw, scale, and wash the fish. Blot dry. Make 5 to 7 diagonal slashes about 1/4 inch deep at even intervals on each side. Rub salt in the slashes and dust all over with flour.

2. Heat the oil in a wok to about 350). Hold the fish by the tail and carefully lower it into the oil. Slide a wok scoop or spatula under the fish to keep it from sticking to the wok and deep-fry until the slashes open, about 2 minutes. Carefully turn the fish upside down, holding it against the side of the wok, and deep-fry another 2 minutes. Continue to turn the fish and deep-fry it until the skin is brown on all sides. Finish by laying the fish flat in the oil and pressing the head down with the scoop until it browns. Remove, drain and place on a large oval serving dish.

3. Pour all but 7 tbsp of the oil out of the wok. Heat until the oil surface ripples. Add the scallions, ginger, garlic, vinegar, and soy sauce. Add the stock, sugar, and cornstarch. Cook, stirring, until the sauce thickens. Pour over the fish and serve.