Kyselo (Czech Sourdough Mushroom Soup)

Zutaten

• Potatoes
• 100 g sourdough starter, ideally made with rye flour
• 15 g dried porcini mushrooms, preferably Central European
• 1 tablespoon caraway seeds
• 1250 ml water
• 1 onion, chopped
• 20 g butter
• 3 chicken eggs
• Salt
• Vinegar
• Chopped green herbs, such as parsley or scallion

Zubereitung

1. Boil potatoes with their skins, then peel them, chop onto small pieces and roast it in a pan (without adding grease).
2. Put 250 ml tepid water into a bowl. Stir in the sourdough starter. Cover with a clean cloth, and let rest at room temperature for 30 minutes to 3 hours.
3. Put 1000 ml water into a stockpot. Add the dried mushrooms and caraway, and boil for at least 15 minutes to make a strong broth.
4. Carefully add the sourdough mixture into the broth, stirring well—there is a danger that the sourdough will shrink into small dumplings.
5. Boil the soup, stirring, until the sourdough thickens the mixture. This should take about 10 minutes.
6. Sauté the chopped onion with butter in a pan. Stir it into the soup.
7. Beat the eggs with a pinch of salt, and scramble them in an ungreased pan. Stir the cooked eggs into the soup.
8. Season the soup to taste with salt and vinegar. It should be mildly sour, flavored primarily by the mushrooms and sourdough.
9. Served the soup hot, garnished with the chopped herbs, with the potatoes as a side dish. Individual diners may wish to add additional vinegar and salt to taste.