Clean, wash and coarsely chop the soup greens and bring to the boil with 2 litres of salt water, bay leaves and peppercorns. Put the meat into it and let it boil at low heat for 45 minutes. In the meantime, clean, peel (leave some green) and wash the carrots. Clean, wash and cut the celery into pieces of about 4 cm. Peel, wash and quarter potatoes lengthwise.
Cook vegetables and potatoes in boiling salted water for about 15 minutes. Remove the crusts from bread and grate finely. Wash and finely chop parsley. Mix bread, parsley, egg yolk and mustard and season with salt and pepper. Remove meat from the stock and let it cool down a little. Spread the bread mixture over the hot meat, press it down and bake it under the hot grill of the oven until golden brown. Heat the fat in a saucepan and sauté the flour in it until golden brown. Deglaze with 1/4 litre of the meat stock and cream and bring to the boil while stirring. Season to taste with horseradish, salt and pepper. Wash the chives, cut into fine rolls and stir in.
Heat the fat in a saucepan and sauté the flour in it until golden brown. Deglaze with 1/4 litre of the meat stock and cream and bring to the boil while stirring. Season to taste with horseradish, salt and pepper. Wash the chives, cut into fine rolls and stir in. Arrange meat and vegetables on a plate. Garnish with parsley. Add sauce extra