Wash the potatoes and cook covered for about 20 minutes. Quench, peel and let cool
Onions peel and chop finely. Fry in hot oil. Add a good 3/8 l water and vinegar, bring to the boil. Stir in broth and mustard, season. Cut potatoes into slices and mix with the hot marinade. Leave to stand for about 1 hour
Cut sausage and cucumber into thin slices and cheese into cubes. Fold everything into the potatoes. Cover and leave to stand for at least 4 hours. Season salad with salt and pepper. Wash and finely chop the chives and sprinkle them over the salad
Drink: cold beer