Soak the beans overnight in cold water. Drain before cooking.
In a large soup pot, place the soaked beans and smoked ham hock. Cover with about 2 liters of water and bring to a boil. Skim any foam that rises, then reduce to a simmer and cook for around 45 minutes.
Add the vegetables — carrots, parsnip, celery, onion, and garlic — along with the sliced sausage, bay leaves, and optional caraway seeds. Simmer for another 30–40 minutes, until beans and vegetables are tender.
Season the soup with sweet paprika, salt, and black pepper. Taste and adjust spices if needed.
Make a roux separately: in a small pan, heat oil or lard, add flour, and stir until golden brown. Remove from heat and mix in 1 teaspoon of paprika. Slowly add a ladle of soup to the roux, stir well, then pour it back into the soup pot, mixing thoroughly. This step adds thickness and depth to the soup.
Simmer for 10–15 more minutes, then remove the ham hock, shred the meat, and return it to the pot. Discard the bone.
Before serving, stir in sour cream or serve it on the side as a garnish. Sprinkle with chopped fresh parsley.