Boil potatoes in skin for about 20 minutes, remove skin. Heat 1 tablespoon of rape seed oil, chop onion finely, saute the onions until soft but not browned in the oil. Add the stock, season thoroughly with salt and pepper to taste. Add the vinegar then the whisk the rest of the oil into the dressing until of creamy consistency. Add Potatoes, then slice cucumber on mandolin or slicer, add dill. Season further to taste.