Clams:
4 pounds steamers or manilla clams, or 7 pounds cherry stones, in the shell and scrubbed
1/4 cup sea salt
1/3 cup cornmeal
Chowder:
2 tablespoons unsalted butter
2 large (7 ounces) onions, diced
2 ribs celery, trimmed and cut into 1/8-inch-thick slices
1 pound waxy potatoes, peeled and cut into 1/2-inch cubes
10 cups fish stock
1/4 cup water
2 ounces (2 slices) slab bacon, rind removed, diced (optional)
2 pounds whitefish fillets, such as hake, cusk, haddock, lingcod, or petrale sole
1 cup milk
1 cup heavy cream
2 tablespoons dry sherry
salt and freshly ground black pepper, to taste
cayenne pepper to taste (optional)
1/2 cup loosely packed Italian (flat leaf)
parsley leaves, for garnish
unsalted butter, for garnish
paprika, for garnish
1. Place the clams in a large bowl or bucket and cover with about 1-1/2 gallons of water and 1/4 cup of sea salt. Stir in the cornmeal. Let stand in a cool place for 2 hours.
2. Melt the butter in a large, broad saucepan. Add the onions and sauté until translucent, about 5 minutes. Add the celery; cook 5 minutes. Add the potatoes and fish stock. Heat to boiling, then reduce heat and simmer until the potatoes are not quite cooked through, about 10 minutes.
3. Meanwhile, remove the clams from the salt water and rinse thoroughly. Place in a large, broad saucepan with the 1/4 cup water and heat to boiling. Cover and cook just until clams open, 3 to 4 minutes. As they open, remove them from the pan with tongs. Discard any that refuse to open. Remove the pan from the heat.
4. Pull the clams from the shells. If the clams are large (such as cherrystones), cut into small pieces. If they are small (steamers or manilla clams), leave them whole. If using steamers, remove the skin from the clams’ siphons before adding to the chowder. Discard the shells, and strain the clam broth through a strainer lined with a double thickness of dampened cheesecloth. Combine the clams and the broth and set aside.
5. If using the bacon, cook in a skillet until it has rendered its fat and is crisp and browned. Drain and refrigerate until later.
6. To the potatoes and broth add the whole fish fillets; cook until just opaque and cooked through, 8 to 10 minutes. Add the clams and their broth. Add the milk and cream. Gently cook over medium-low heat. Add the sherry and season with salt and pepper. Stir gently so the fish doesn’t break up too much. Cool thoroughly, then cover and refrigerate for at least 8 hours (or overnight) before serving.
7. Just before serving, bring chowder to a simmer over medium-low heat. Add cayenne pepper, to taste. Reheat the bacon in a small skillet over very low heat.
8. To serve, ladle the chowder into shallow bowls. Garnish each bowl with a piece of butter, a sprinkle of parsley, and cayenne and/or paprika. Serve the bacon on the side for sprinkling on top.