Clean, wash and cut the soup greens into pieces. Bring approx. 2 litres of salt water, soup greens, bay leaves and peppercorns to the boil. Wash the meat, add it and let it simmer at low heat for about 1 1/2 hours.
In the meantime, peel, wash and halve the potatoes. Clean the leek, wash and cut into rings. Peel and wash carrots and cut them into thin slices. After 1 hour cooking time, skim approx. 400 ml of the meat stock.
Cook the potatoes for about 20 minutes, the carrots and leek for about 10 minutes. Whisk cream and flour. Add to the vegetables while stirring constantly. Bring to the boil briefly. Peel and wash the horseradish. Grate about 2 teaspoons finely.
Season the sauce with horseradish, salt, pepper and lemon juice. Take the roast out of the broth and cut it open. Arrange with the vegetables on a preheated plate. Pour some sauce over it. Wash the chives and cut into small rolls.
Grate or cut the remaining horseradish into very fine strips. Sprinkle over roast. Serve garnished with parsley if desired.