Boil the potatoes in their skins until tender, about 30 minutes. Then rinse with cold water, peel and cut into small slices.
Hard boil the eggs, peel, cool and chop coarsely. Remove skin from butter fish. Cut the flesh of the fish into small slices.
Cut the cucumbers in half lengthwise, and then in halves of circles. Peel the apple, cut into quarters, cut into thin slices, sprinkle with lemon juice. Chop the green onion.
For dressing, mix all ingredients until smooth. Mix all the salad ingredients, pour over the dressing, let it brew in a cool place for about 20 minutes. and serve.