Peel and slice the onion. Pour 1 tablespoon of olive oil into a heavy-bottomed sauce pan and sauté onions on low heat.

Cut carrot, potatoes, beets, and apple into small cubes.

Add the cubes to the saucepan. Stir regularly with a wooden spoon.

Add hot broth. Let it simmer for 30 minutes, until the diced beets and potatoes are tender.

While the soup is cooking, slice the red cabbage into thin slices using a mandoline or a sharp knife.

Add the red cabbage and cider vinegar to the soup. Cover and cook for another 5 minutes. Check the seasoning of the soup and add salt if necessary.