To begin, scrub the potatoes thoroughly and place them in a large pot of salted water. Bring to a boil and cook for 15-20 minutes, or until the potatoes are tender but not falling apart. Test doneness with a fork, it should pierce the potato easily. Drain and allow the potatoes to cool slightly.

While the potatoes are cooling, prepare the dressing. In a small saucepan, heat the broth over low heat until warm. Stir in the vinegar, mustard, sugar, and a pinch of salt and pepper. Mix until the ingredients are well combined and the sugar has dissolved. Set aside to keep warm.

Once the potatoes are cool enough to handle, peel them gently with a paring knife. Cut the potatoes into even slices, approximately 5 mm thick, and transfer them to a large mixing bowl. Uniform slicing ensures an even distribution of flavours.

Pour the warm dressing over the sliced potatoes. Add the finely chopped onion and gently toss the mixture with a wooden spoon or spatula, being careful not to break the potato slices. The warmth of the dressing helps the flavours penetrate the potatoes.

Allow the potato salad to rest at room temperature for 20-30 minutes, tossing occasionally. This resting period is crucial for the potatoes to absorb the dressing and develop their full flavour.

Taste the potato salad and adjust the seasoning with additional salt, pepper, or a splash of vinegar if needed. Stir in the sunflower oil, which adds a subtle richness and helps bind the flavours.

For a traditional touch, garnish the salad with freshly chopped chives before serving. This adds a pop of colour and a mild onion like flavour that complements the dish beautifully.

Serve the Kartoffelsalat slightly warm or at room temperature. It pairs wonderfully with schnitzel, sausages, or grilled meats. For an authentic presentation, arrange it in a serving bowl and sprinkle extra chives on top. Offer additional mustard or pickles on the side to enhance the meal.