Wash the meat and let it drip off. Peel and halve the onion and fry it in a pan without fat for about 5 minutes on the cut surface until dark. Clean and wash the soup greens. Cut carrots and celery into 2-3 pieces.
Cut the remaining vegetables roughly into pieces. Bring 1 1/2 - 2 litres of water, bay leaf, cloves, some salt, onion, peppercorns and soup vegetables to the boil in a large pot. Add meat and simmer at medium heat for about 2 hours.
In the meantime, skim off the resulting foam with a skimmer. Wash the potatoes and cook in boiling water for about 20 minutes. Drain potatoes, rinse with cold water and peel. Wash the rosemary and chop finely, except for a little to garnish.
Press the potatoes through a potato ricer and let them cool down a little. Knead in quark, 200 g flour and rosemary, season with salt. On a work surface sprinkled with flour, form rolls about as thick as your thumb and cut into pieces about 4 cm long.
Form oval gnocchi and press in grooves with a fork. Clean the carrots, leaving some green and wash them. Cook in boiling salted water for 5-6 minutes. Cook gnocchi in boiling salted water for about 5 minutes, then drain and keep warm.
Remove the prepared boiled beef from the stock and keep warm. Pour stock through a sieve and measure 500 ml. Melt the fat in a saucepan, dust with 30 g flour and sauté. Deglaze with the measured stock and cream while stirring.
Stir in horseradish and bring to the boil. Season with salt, pepper and lemon juice and simmer for 1 minute. Wash parsley, shake dry and chop finely. Cut the roast into slices. Arrange on plates with carrots, gnocchi and some sauce.
Sprinkle with rosemary and parsley. Remaining sauce extra pass.