Place the salt pork in the soup pot and cook until the fat renders; add the onions, carrots, celery, leeks and green peppers to the fat and cook, stirring, until the vegetables are tender.
Add the garlic and cook until it becomes aromatic, then add the clam juice (or water, if using), the reserved juice from the clams, the diced tomatoes, the bay leaf, the thyme, and oregano; simmer for 30 minutes.
Add the potatoes and simmer until they are tender, about 20-25 minutes more.
Skim the soup for fat or chill to allow it to rise and remove; discard bay leaf.
If chilled, heat through, then add clams and seasonings (salt, pepper, Tabasco, Worcestershire, and Old Bay).
Serve when hot, about 2-3 minutes after adding clams.