This is a vegan version of a traditional recipe that I had in a little Polish restaurant in Doncaster. The soup was a thin clear broth with sauerkraut in it, and on the side of the dish a pile of mashed potatoes that you mixed into the soup as you ate it to thicken it.
The original version was made with a meat stock, and the mash thickener had finely chopped ham in it and maybe some fried onions as well. The additions to the mash can be changed depending on what you have in your cupboard, just fried onions and or garlic would work well, finely chopped fried peppers too.

For 1 portion

250 – 300 ml clear stock

70 grams sauerkraut plus a tablespoon of its salty liquid

1 medium potato – peeled and cut into smallish cubes

1 medium sized strongly flavoured mushroom – chopped into small dice

1 clove garlic – finely chopped

20 grams hazelnuts – roughly crushed

1 tablespoon olive oil

freshly ground black pepper

Heat the oil in a small saucepan and once hot add the garlic and mushrooms. Fry stirring regularly for about 5 minutes.

Add the potatoes, stir to mix in, the add enough boiling water to only just cover the potatoes. Cover and simmer until the potatoes are cooked and soft.

While the potatoes are cooking, put the stock and sauerkraut in another pan and bring to a simmer. Check the seasonings adding salt and black pepper as needed.

Once the potatoes are cooked pour off any excess cooking liquid into the soup. Mash the potato mix. Add the crushed hazelnuts and mix in.

Serve the soup with a little mound of the potato mix to one side.