Cut the onions into 1 cm cubes and sauté them in the oil, cut the carrots, celery, plums and potatoes into 1 cm cubes and add to the saucepan and lightly roast, sprinkle with the powdered sugar and caramelize lightly. Pour the broth over it and let it simmer with the cinnamon and spices for about half an hour.
Then mix with the hand blender and bring to the boil again.
The soup is served with firm milk foam.
It is nice to arrange the soup in a coffee cup and serve it as a potato-plum cappuccino with a milk froth cap.