Heat the oil in a large saucepan. Peel and chop the onion. Sweat in the fat. Add the sauerkraut and let it simmer briefly.
Mix with the broth and let simmer for a while. Season with salt and pepper and fold in the caraway seeds.
In the meantime, peel the potatoes and cook them in a separate saucepan. Chop the potatoes a little with a fork and mix with the sauerkraut. Finally add the pineapple pieces and stir well.