Place the butter in a large pot and let it melt. Then add the white part of the leeks, cut into thin slices, and cook over gentle heat until tender.
Add the peeled and chopped potato, broth, cream and a teaspoon of balsamic vinegar pearls, and cook for about 30 minutes or until the potato is tender.
Blend the cream and add salt and white pepper to taste. Serve and decorate with chopped fresh chives and add balsamic vinegar pearls.