Wash the potatoes thoroughly and boil it. Cut into slices without removing the peel.
In another pan, boil hard-boiled eggs and cut into half rings.
Cut the cucumbers into small cubes.
Chop red onion.
Make the sauce. Combine mayonnaise, mustard, salt, and pepper. Mix well.
Combine all ingredients in a large bowl, season with sauce and mix. Put in a salad bowl and sprinkle with chopped green onions.