We think the combination of shrimp and cod keeps thing interesting, but you could easily make this soup with just one or the other; simply double the quantity of whichever you choose. Sautéing the croutons in oil keeps them from getting soggy in the soup. The clam juice here will not make the soup taste like clams, since the juice is diluted with water and juice from the tomatoes; it just punches up the fish flavor. Plus: More Soups and Stews
How to Make It
In a large pot, melt the butter over moderately low heat. Add the onion, celery, garlic, and 3/4 teaspoon of the salt. Cook, stirring occasionally, until the vegetables start to soften, about 10 minutes. Add the wine, tarragon, clam juice, tomatoes, and water. Bring to a boil. Reduce the heat and simmer for 10 minutes.
Meanwhile, put a medium frying pan over moderately low heat. Toss the bread cubes with the oil and the remaining 1/4 teaspoon salt; add them to the pan. Cook, stirring frequently, until crisp and golden brown, about 5 minutes. Remove from the heat and toss the croutons with 1/8 teaspoon pepper and 2 tablespoons of the parsley.
Stir the cod and shrimp into the soup. Cook, stirring occasionally, until the seafood is just done, 3 to 5 minutes. Stir in 1/4 teaspoon pepper and the remaining parsley and serve the soup topped with the croutons.