Cover the beans and soak them in approx. 1 l of cold water overnight. The next day, drain, bring to the boil with about 1 l of fresh water, cover and simmer over a low heat for about 1 hour. Drain and let it cool down a bit.
Peel and finely dice the onion and garlic. Wash the parsley and dab dry. Put something to garnish aside, chop the rest. Puree the beans and 2-3 tablespoons of water. Knead with onion, garlic, egg, breadcrumbs and parsley.
Season to taste with salt and pepper, let it rest for a while.
Clean the mushrooms, possibly wash and halve them. Clean, wash and cut spring onions into fine rings.
Form approx. 12 roasts from the bean mixture with moistened hands. Heat 2-3 tablespoons of oil in a coated frying pan. Fry the roasts for 3-4 minutes on each side.
In the meantime, fry the ham cubes in 1 tablespoon of hot oil and remove. Fry the mushrooms in the hot frying fat. Steam spring onions briefly. Add ham and season. Briefly sauté flour in it and stir in 1⁄2 l water.
Bring to the boil, simmer for about 5 minutes. Refine sauce with sour cream and season to taste. Arrange everything, garnish with parsley.