Slice steak across grain into thin strips and place in small bowl. Combine soy sauce, wine, garlic, sesame oil and red pepper flakes in small bowl and set aside. Heat a large heavy skillet or wok over high heat. Add 2 teaspoons of the oil and heat until almost smoking. Add the beef and cook until browned and cooked, about 2 minutes, then remove to a bowl. Add the remaining teaspoon of vegetable oil and add the onion and red pepper. Cook, stir-frying until crisp-tender, about 2 minutes. Add the beef and the sauce to the onions and red pepper, and stir-fry until heated through. Stir in the grapes and scallions and cook 30 seconds longer. To serve, line the bottom of a platter with the cabbage, top with the hot beef mixture, and sprinkle with sesame seeds.