Wash the potatoes and cook in plenty of boiling water for about 20 minutes. Rinse under cold water, drain and peel. Cut the potatoes into slices with a colored knife.
Heat the oil in a pan. Fry the potatoes for about 15 minutes while turning them. Season with salt and pepper. Cut cucumbers into slices, except for 2 pieces. Cut the remaining cucumbers in half lengthwise and cut into fans.
Wash the dill, shake dry. Pluck little flags from the stalks, except for something to garnish, and cut finely. Cut salmon into strips. Arrange roast potatoes and one tablespoon of crème fraîche each on plates, sprinkle with salmon, dill and cucumber slices.
Garnish with dill, caviar and cucumber.