Boil unpeeled potatoes. Cut cucumber lengthwise and remove seeds and cut into thin slices and place in bowl. add salt. cut onion in thin slices and soak in cold water until youUre ready to use them. Remove skins from cooked potatoes and cut potatoes lengthwise into pieces 1 inch wide. Drain cucumber and drain onions well. Place all ingredients into large bowl and mix well. Adding apple slices will surprise your taste buds. this potato salad tastes very similar to the one you would buy in Japan.