1. With a cleaver or sharp knife, cut the flank steak lengthwise into strips 1½ inches wide, then crosswise into ¼-inch slices.
2. In a large bowl, mix the wine, soy sauce, sugar and cornstarch. Add the steak slices and toss with a large spoon to coat them thoroughly. The steak may be cooked at once, or marinated for as long as 6 hours.
3. Place the peppers, ginger root and oil within easy reach.
TO COOK:
1. Set a 12-inch wok or 10-inch skillet over high heat for about 30 seconds. Pour in a tablespoon of the 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. Immediately add the pepper squares and stir-fry for 3 minutes, or until they are tender but still crisp. Scoop them out with a slotted spoon and reserve.
3. Pour 3 more tablespoons of oil into the pan and heat almost to the smoking point. Add the ginger, stir for a few seconds, then drop in the steak mixture. Stir-fry over high heat for about 2 minutes, or until the meat shows no sign of pink. Discard the ginger.
4. Add the pepper and cook for a minute, stirring, then transfer the contents of the pan to a heated platter and serve.
To Serve: 2 to 4 as main course or 4 to 6 as Chinese Meal
