Choose Cucumbers with few if any seeds. Peel them, cut them into slices no more than 1/4 inch thick. Chill the Cucumber slices and half again as many really fresh Mung Bean Sprouts in a glass bowl covered with plastic. In another glass bowl, whisk together the seasoned rice wine vinegar, sugar, soy sauce and sesame oil. (A little bit of sesame oil goes a long way.) Heat ever so briefly in the microwave, and whisk to make sure that the sugar is dissolved. Chill.
Just 15 to 20 minutes before serving, pour the rice wine dressing over the peeled Cucumbers, Mung Bean Sprouts and chopped Scallions. Mix gently to ensure consistent coverage and marinate in the refrigerator for no more than 20 minutes. (The Cucumbers become increasingly more soft and pliable and lose their crisp bite.) To serve, remove the sliced Cucumbers and Scallions from the marinade and serve cold. (For fun, you can also peel the Cucumbers and slice them into long thin ribbons with a kaasschaaf (a cheese plane), or add very thin slices of Red Onion for color.) Serves 4 to 6.