1. Peel off the thin outer membrane covering the kidneys, if the butcher has not already removed it, with a cleaver or sharp knife. Split the kidneys in half lengthwise and cut away the small knobs of fat and any tough membrane surrounding them.
2. Place the kidney halves flat side down on a chopping board and score their surfaces diagonally to create a crisscross pattern, cutting about two thirds of the way down into them and spacing the cuts about ¼ inch apart.
3. Then cut the kidneys crosswise into 1-inch slices, and cut the slices into strips about 2 inches long.
4. Wash the scallops under cold running water, pat them dry with paper towels and cut them horizontally into slices ¼ inch thick.
5. Have the above ingredients, and the oil, wine, ginger, scallions, soy sauce, salt, sugar and the cornstarch mixture within easy reach.
TO COOK:
1. Set a 12-inch wok or 10-inch skillet over high heat for 30 seconds. Pour in 2 tablespoons of oil, swirl it about in the pan and heat for another 30 seconds, turning the heat down to moderate if the oil begins to smoke.
2. Add the scallops and stir-fry for only 1 minute, or until they turn white but not too firm. Immediately pour in the wine and add the salt, stir well, and, with a large spoon, transfer the scallops to a plate.
3. Pour the remaining 2 tablespoons of oil into the pan, heat for about 30 seconds, and add the ginger and scallions. Stir for a few seconds and drop in the kidneys.
4. Stir-fry over high heat for 2 minutes, or until their edges begin to curl. Then add the soy sauce and sugar. Return the scallops and their accumulated juices to the pan, and mix with the kidneys for a few seconds.
5. Give the cornstarch mixture a quick stir to recombine it and add it to the pan. When the kidneys and scallops are coated with a light, clear glaze-this will take no more than a few seconds-transfers the entire contents of the pan to a heated platter and serve at once.
To Serve: 4 as a main course or 4 to 6 as part of a Chinese Meal
