Cook potatoes and eggs until tender. I do not peel off such young animals, but just wash the potatoes well with a brush.
Finely chop the onion.
While everything is cooking, prepare the sauce – mix yogurt, mustard, onion, salt and pepper.
Cut the finished potatoes in half while still hot, and then each half into 2-4 parts, depending on the size. Quickly, before everything cools down, cut the eggs and cucumber into small cubes.
Put everything in a salad bowl, season with sauce.