Soak salt beef in water mixed with vinegar overnight.  Wash peas, soak in 5 cups water overnight, drain.  Add salt to water, bring to a boil.  Add peas, lower heat.  Simmer about 1 1/2 hours or until tender.  Puree peas through sieve or blender.  While peas cook, place meat into a pot.  Add water to cover, about 6 cups.  Bring to a boil.  Add thyme & cook until done, about 1 1/2 hours, then add celery, carrots, onion & potatoes & cook 30 minutes longer.  Remove meat & vegetables from broth.  Stir broth into pureed peas and simmer until thick.  Add cooked meat and vegetables.