Place clams in soup kettle, cover with water, and steam open. Remove clams from shells and mince fine; reserve. Strain clam liquid and reserve. Saute pork and onions in butter until onions are clear. Add tomatoes and simmer 5 minutes, stirring. Add celery, carrots, parsley, basil, thyme, bay leaf, garlic and soy sauce. Stir in correct amount of liquid (clam cooking water plus additional water if needed); simmer, covered one hour. Add potatoes and simmer 15 minutes. Add clams and simmer another 8 minutes. Adjust seasoning if necessary. Serve immediately, with crackers.