5 dozen littleneck clams (quahogs), scrubbed
3 cups water
1 ounce salt pork, rinsed well and cut into lardons
1 tablespoon unsalted butter (optional)
1/2 large yellow onion, cut into small dice (1 cup)
1 large russet potato, peeled and cut into 1/2-inch dice (2 cups)
Coarse salt and freshly ground black pepper
1 sprig thyme
1 dried bay leaf
1/2 cup heavy cream

1. Cook clams and make broth: Combine clams and water in a medium stockpot, and then cover and bring to a boil. Cook until clams have opened, 5 to 6 minutes (discard any that remain closed). Use a slotted spoon to remove clams. Strain the broth through a fine sieve lined with a coffee filter; you should have about 4 cups (if not, add a little water). When clams are cool enough to handle, remove the meat from the shells and coarsely chop. Discard shells.
2. Build the flavor base: Rinse the pot and dry completely. Cook the salt pork over medium heat until some of the fat has rendered and the remaining meat is light golden, about 3 minutes. (If there is not enough fat to coat the bottom of the pot, add the butter). Add the onion and cook until translucent, about 3 minutes, stirring once or twice.
3. Add broth and finish soup: Return the strained clam broth to the pot, along with the potato, thyme, and bay leaf; season with salt and pepper. Bring to a boil, and then reduce to a simmer and cook until the potato is tender but not falling apart, 6 to 8 minutes (if desired, mash a few against the side of the pot to thicken the broth slightly). Stir in clams and cream and cook just until heated through, no more than a minute or so. (Do not boil, or cream will separate and clams will toughen.) Season with salt and pepper and serve immediately.

Makes 6 cups.