Dice the Kasseler. Put about 1/2 liter of water and caraway seeds in a soup pot together with sauerkraut, diced onions. Let simmer for approx. 45 minutes.
In the meantime, peel and dice the potatoes and cook them in a separate saucepan.
Add the potatoes to the sauerkraut and add the rest of the water (preferably so much until everything is just covered). Bring everything to the boil again and add broth to taste.