Fresh Clams: Place the clams and 4 cups of water over medium high heat. Cover and cook until they have opened, about 10 minutes. Discard any clams that fail to open! Strain the broth and reserve. Remove the clams from the shells and set aside.
Canned Clams: Drain the clams, strain the liquid, refrigerate and reserve both .
- Melt the butter on medium low heat in a soup pot. Add the bacon and cook, stirring occasionally until the fat has rendered and the pork has started to brown – about 5-7 minutes. Remove the bacon and drain on a paper towel
- Add the onions, celery, green peppers and carrots to the pot and cook stirring until the vegetables are soft but not brown, about 10 minutes
- Stir in the garlic and potatoes, continuing to cook until they have begun to soften – about 5-7 minutes more
- Add the clam broth from the fresh clams, or 3 cups of water and the strained, canned clam juice, the bay leaf and thyme sprigs
- Partly cover the pot and low simmer until the potatoes are tender, about 10-12 minutes more. Test to see how a potato smashes with a spoon
- Stir in the tomatoes and heat them through
- Add the clams and reserved bacon, stir to combine and adjust salt and pepper to taste
- Return soup to a simmer, then remove from heat and discard the bay leaf and thyme
- Let the chowder rest for 30 minutes to give the flavors time to meld, then reheat before serving if necessary
- Garnish with chopped parsley and serve with oyster crackers on the side