Peel and dice the potatoes. Peel and dice the onions. Cut the smoked salmon into strips. Wash the parsley, shake dry, pluck the leaves off and chop. Drain the sauerkraut in a sieve (you may need to blanch it briefly beforehand so that it loses some of its acidity, and rinse off with cold water).
Heat 1 tablespoon of oil and sauté half of the onion cubes. Add the potatoes, pour in the vegetable stock and cream. Season with salt, pepper and caraway seeds. Simmer for about 15 minutes, then puree and season to taste again.
Heat 1 tablespoon of oil and sauté the other half of the onion cubes. Add the drained sauerkraut and sauté briefly, then fold in the parsley.
Serve the soup with sauerkraut and spread the salmon strips on top.