Peel the potatoes, cut into cubes, boil and then leave to cool. Boil the eggs hard, also let them cool down.
Put the cooled potatoes in a salad bowl. Drain the beans, wash them off and add them to the potatoes. Chop the onion very finely and also add to the potatoes. Wash the tomatoes, cut them into small pieces and add to the salad. Set aside a tomato for garnish.
Season the salad with oil, vinegar, salt, pepper and sugar. Peel and quarter the eggs and arrange on the salad. Quarter the tomato and arrange on top of the salad as well.