For the apple salad, first peel the onions, chop finely, mix with the white wine vinegar in a small bowl and let stand.
Boil the potatoes with their skins, let them cool down a bit, peel them and cut them into not too thin slices.
Pour the hot vegetable soup over the potato slices in a salad bowl and stir through. Add the onions with the vinegar, oil, mustard and sugar and mix well. Let it stand for at least half an hour.
Season with sugar and salt and decorate with chives and flowers.
The potato salad tastes lukewarm or cold.