Cut the liver into pieces and roll in flour. Then fry in a frying pan on each side.
Cut the onion into rings and add to the liver, also use sour cream, pepper and salt. Mix well, pour in water and simmer for 15 minutes.
Grate the cheese and eggs on a fine grater. Add butter and mix.
Grind the liver in a food processor or blender and place on cling film.
Place the filling and roll up the roll using the film. Let it cool.