Peel the potatoes and cut them into large pieces.
Boil the potatoes in a pot until cooked through.
Boil the eggs in boiling water, cool them, and peel off the shells.
Cut the boiled potatoes and eggs into bite-sized pieces.
Finely chop the onion and cucumber.
In a bowl, add the potatoes, eggs, onion, cucumber, mayonnaise, salt, and pepper, then mix well.
Transfer to a serving dish to finish.