Boil the potatoes with salt and caraway seeds into jacket potatoes for about 20 minutes, then peel them and cut the halved potatoes into slices. Steam the diced onions in hot oil until translucent, then add the vegetable stock and cook gently for about 10 minutes. Season to taste with salt, pepper and white wine vinegar. Stir some sunflower oil into the brew. Halve the cucumber lengthways and cut into fine slices, mix in the dill, add everything to the potatoes and mix again. Then pour the onion stock over the potatoes and stir well, add salt and pepper to taste and let it steep for at least 1 hour. The salad tastes best when it can steep in the refrigerator for a night.