This Scottish-style chowder is made with smoked salmon, but you can try other hot-smoked fish, like trout or haddock.
Bring clams, thyme sprigs, and 4 cups water to a simmer in a large pot. Cover; cook until clams open, 5 to 10 minutes. Transfer to a bowl, discarding any that remain closed. Strain liquid into a bowl. Reserve 12 clams; coarsely chop meat from remaining ones.
Melt butter in pot over medium. Add leeks; cook, stirring occasionally, until soft, 5 minutes. Stir in vermouth; cook until almost evaporated, 2 minutes. Add celery, potatoes, and clam liquid. Simmer, partially covered, until potatoes are tender, 15 to 20 minutes; mash a few with the back of a spoon to thicken soup. Stir in cream, salmon, and all clams. Cook until heated through, 1 minute. Season with pepper and serve, topped with thyme leaves.
Serve it with thick slices of brown bread.