Place whole potatoes in a large pot, cover with lightly salted water, and simmer until a knife slides through easily. Drain and let the potatoes cool just enough to handle.

When cool enough, peel the potatoes and cut them into about 1/4-inch slices. Transfer the slices to a large mixing bowl and set aside.

Combine the chopped onion, prepared bouillon (stir 4 teaspoons granules into 1 1/2 cups hot water), white vinegar, a few splashes of Essig Essenz, 3/4 tablespoon salt, white pepper, sugar, and mustard in a medium saucepan.

Bring the mixture just to a boil, then remove the pan from the heat immediately so the flavors meld without reducing too much.

Pour the hot dressing over the sliced potatoes, cover the bowl, and let the potatoes absorb the liquid for at least one hour at room temperature.

After the resting period, gently fold in the oil and taste; adjust salt and pepper as needed. If there is excess liquid, serve portions using a slotted spoon so the salad isn’t soggy.

Garnish with chopped fresh chives and serve the salad at room temperature. For best flavor, refrigerate overnight and bring to room temperature for about 30 minutes before serving.