Put beef in a large pot and cover with cold water. Add all other ingredients except cabbage and bring to a boil with the lid off the pot. Turn to simmer and cook for 3 hours. Skim fat from top as it rises. Remove the thyme, parsley and onion. Add cabbage. Simmer for 20 minutes until cabbage is cooked. Remove the meat and cut into pieces. Place on center of a large platter. Strain the cabbage and season it heavily with black pepper. Surround the beef with the cabbage, carrots and potatoes. Serve with horseradish sauce. Horseradish Sauce: Whip cream until it stand in peaks. Fold in horseradish.