Place the meat, whole onion and salt & pepper in a large soup pot; fill with water and bring to a boil. Skim fat off top. Reduce heat to medium, cover pot and cook for 1 hour. Break up dried mushrooms into small pieces and soak in hot water for 10 to 15 minutes; add to soup. Add Manischewitz vegetable soup mix, including seasoning packet, carrots, celery, parsnips and potatoes. Cook soup over medium flame for 1 to 2 hours. Break meat apart and remove bones. Break onion apart. Add salt & pepper to taste. Serve in bowls garnished with fresh dill.