It’s hard to go wrong with this soup since the flavors of leeks, mushrooms and cider finished with heavy cream make a delicious base for just about anything. The fish becomes almost superfluous.
This version is thickened with lightly toasted bread, but you can also use potato or sweet potato. Just cook 2 medium-size peeled and sliced potatoes or sweet potatoes along with the squash at the beginning.
3 pounds whole fish
Fish Broth
1 medium onion, coarsely chopped
3 leeks, green part only, but whites reserved, coarsely chopped
5 cups hard cider or 3 cups apple cider combined with 2 cups water
1 bouquet garni
Soup
2 Tablespoons unsalted butter
18 small mushrooms, quartered
1/2cup heavy cream
1 Tablespoon parsley or chervil, chopped
2 Tablespoons Calvados
1/3 to 1/2 cup cider vinegar
Salt and white pepper to taste
To prepare the fish broth, have the fishmonger gut and fillet the fish and remove the skin. Be sure to save the fish head and bones. When you get the fillets home, check them carefully and remove any bones.
Make a fish broth by thoroughly rinsing the head and bones in cold water and combining them with the onions, leek greens, cider and bouquet garni in a 4-quart pot. Bring the broth to a slow and simmer for 30 minutes, skimming off any froth that floats to the top. Strain the broth through a medium-mesh strainer.
At the last minute, slice the white parts of the leeks finely and put them in a 4-quart pot with the butter. Cook them gently until they soften, for about 10 minutes. Add the mushrooms and cook gently for 3 minutes more.
Just before serving, arrange the fish in one layer in the pot with the leeks and mushrooms. Pour the simmering fish broth over the fish. Poach the fish fillets for about 8 minutes for each inch of thickness and distribute them among soup bowls with a slotted spoon.
Add the cream, parsley, Calvados and a tablespoon of the cider vinegar to the broth. Taste it, adjust the vinegar, and season with salt and pepper. Ladle the broth with the mushrooms and leeks over the fish.
Suggestions and variations
Apple wedges lightly sautéed in butter make a lovely additional garnish for the soup.
Yield: 6 servings