Freeze beef until partially firm, cut into very thin slices. Combine soy sauce, rice wine vinegar, and sugar in a small non-metallic bowl. Add beef slices, toss to coat evenly. Cover and refrigerate 8 hours or overnight.
Drain beef, discard marinade. Grill beef over medium-hot coals for 2-3 minutes or until desired doneness (can be cooked in a stove-top grill pan or a wok).
Meanwhile, prepare Korean dressing. Place sesame seeds in a small nonstick skillet. Cook and stir over medium heat until lightly browned and toasted, about 5 minutes. Cool completely. Crush sesame seeds, using mortar and pestle or wooden spoon; transfer to a small bowl. Add orange juice, rice wine vinegar, soy sauce, sesame oil, ginger, sugar, garlic and red pepper flakes. Blend well.
Cook noodles in boiling water 1-2 minutes or until tender; drain and rinse under cold water. Arrange noodles on platter.
Combine cabbage, bell peppers, radishes, carrot, green onions and beef in a medium bowl. Add Korean dressing; toss to coat evenly. Serve over noodles.