Beef and Cabbage Borscht

Cut ribs in half. In Dutch oven, cover beef ribs and soup bone with water and bring to boil; reduce heat and simmer until meat is no longer pink, about 10 minutes. Drain an rinse ribs and bone; return to Dutch oven. Add onions, tomatoes and 4 cups water; cover and simmer over medium-low hear for 1 hour. Add cabbage, salt and pepper; simmer, covered, for 1 hour. Remove ribs and bone. Remove meat from ribs; trim off fat and chop meat. Remove marrow from bone. Return meat and marrow to pot. Stir in lemon juice, tomato paste and sugar; simmer for 20 minutes.