Peel the onion and cut into circles.

Boil the water, add vinegar, mix with onion, and cool. Pour the water out.

Cut hard-boiled eggs and mix with the prepared onion.

Cut the cucumber into circles, add salt, serve on a dish, place onion circles and eggs over it, top with mayonnaise.

Serve cool. Decorate the dish with salad leaves and parsley greens.