Kyselo Czech Sourdough Soup

The day before:

1. Place 1 handful dried porcini mushrooms in a saucepan and cover them with approximately two cups of water. Allow them to soak overnight.
2. Dissolve 1 cup sourdough starter in a cup of lukewarm water and leave it on the kitchen counter overnight. Preparing the mix this way ensures the soup will be mildly tart, not overly sour.

Making the sourdough soup:

1. Before you start: If you want to serve peeled potatoes with the soup, cook them with the skin on. Plan for about two small potatoes per serving.
2. Bring the soaked mushrooms to a boil and simmer over low heat for 15 minutes.
3. Remove the saucepan with the mushrooms and broth from the heat source. Add the mixed sourdough starter and whisk well. Pour in 5 cups water, then add 2 teaspoons salt and 1 teaspoon caraway seeds to the base.
4. Bring the soup to a boil, then reduce the heat to about medium and cook for 15-20 minutes. Remember to stir occasionally, as the sourdough flour can settle at the bottom of the pot and burn.
5. Peel and finely chop 1 onion. Heat 1 Tablespoon lard or oil in a frying pan and sauté the onions until golden brown, stirring frequently. Crack 5 eggs into the pan with the onions, stir, and fry them together until cooked.
6. Add the fried eggs to the finished sourdough soup and season with salt if needed. Serve the soup over cooked, peeled potatoes.