Boil potatoes with skin.
While potatoes are boiling chop onion finely, place into a big bowl.
Combine onions with oil, vinegar and mustard, mix well.
Pour 250ml (half of the amount) HOT beef or vegetable broth over it.
When potatoes are done remove them from the water, peel, and let cool off.
Cut into very thin slices (potatoes must not be hot).
Add them to onion broth and mix well with a wooden spoon.
Add more broth if necessary; the salad should NOT be too dry and should NOT be swimming in broth.
Add salt, nutmeg and pepper to taste.
Let salad sit for some time to see if it will be still moist, add more broth if needed.
Add the chopped parsley or chives on top.
