Place potatoes in a pot of cold water and bring to a boil. Let cook for about 20 minutes.
While the potatoes are cooking, prepare the dressing: Finely dice the onion and add the diced pieces in a bowl, add the vegetable stock powder, and pour in hot water.
Add the oil, vinegar, mustard, salt, and a little fresh pepper. Stir.
When the potatoes are done (prick them with a fork to see if they're done), rinse them briefly in cold water. Then peel and slice while still warm, but not too thin (otherwise they all break).
Pour the warm dressing over the warm potatoes, stir gently, and let the potato salad sit at room temperature for at least an hour.
Sprinkle with fresh chives before serving.
Video
Notes
Cook the potatoes until done, but not too mushy, or you'll end up with a mashed potato salad.
Yes, 250 ml (1 cup) of liquid (broth) may seem like a lot, but the potatoes will soak up the dressing nicely. In the end, the salad ends up being creamy.
Therefore, please do not add more seasoning right away, but let the salad soak for at least an hour first.
The potato salad can be prepared in advance and tastes even better the next day.