1. Wash the potatoes and cook them in salted water until tender. Drain the water and let the potatoes cool down slightly, then place them in a bowl. They should still be warm when you add the dressing.

2. Peel and slice the red onion into thin rings. Wash the cucumber and chop it into small pieces, then chop the fresh dill. Rinse the arugula leaves under cold running water.

3.To make the dressing, whisk together the neutral oil, white vinegar, Dijon mustard, whole-grain mustard, salt, and pepper in a bowl using a whisk, or combine them in a jar with a lid and shake vigorously.

4.Pour the dressing over the warm potatoes, then add the sliced onion, chopped cucumber, capers, dill, and arugula.

5.Mix everything together well to combine. Serve the potato salad with your choice of grilled sausage, such as bologna sausage or knockwurst, accompanied by a dollop of mustard or a side of ajvar relish.