SERVES 4 TO 6
Fennel and orange zest may seem unusual in fish soup, but this natural duo—common players in many seafood dishes—makes a great match for mild, delicate fish like cod. Using store-bought clam juice in place of making your own fish stock eliminates the need for the extra cooking step while still providing a perfect broth base. This soup is a great main course for a dinner party, not only because it’s easy and elegant but also since much of the work can be done in advance. Prepare it ahead, if you like, until just before the fish is added. Then all you need is a few quick minutes to finish the dish. Float the buttery garlic toasts on top, or use them to sop up the last spoonfuls of soup.
3 tablespoons extra-virgin olive oil
1 small fennel bulb, coarsely chopped (about 1½ cups); plus 1 tablespoon finely chopped fronds for serving
1 small onion, coarsely chopped (about 1¼ cups)
2 celery ribs, coarsely chopped; plus 3 tablespoons finely chopped leaves from the inner heart of the bunch for serving
3 garlic cloves, finely chopped
½ cup dry white wine or Pernod
3 (8-ounce) bottles clam juice (3 cups)
1 (28-ounce) can whole tomatoes, tomatoes crushed by hand, juices reserved
4 fresh thyme sprigs, or ½ teaspoon dried thyme
Finely grated zest of 1 navel orange (about 1½ teaspoons)
¼ teaspoon red pepper flakes
Kosher salt
2 pounds firm white fish fillets such as halibut, cod, red snapper, or tilapia, cut into 1-inch cubes
Freshly ground black pepper
3 tablespoons unsalted butter
1 large garlic clove, thinly sliced
1 fresh thyme sprig, or pinch dried thyme
¼ teaspoon kosher salt
½ baguette, cut on the diagonal into ⅓-inch slices
For the soup: In a 6- to 8-quart Dutch oven or wide, heavy-bottomed pot with lid, heat the oil over medium heat. Add the fennel, onion, celery, and garlic and cook, stirring occasionally, until the vegetables begin to soften, about 5 minutes. Add the wine and cook until the liquid is mostly evaporated, about 5 minutes. Stir in the clam juice, tomatoes and their juices, thyme, orange zest, pepper flakes, 1 teaspoon salt, and 1½ cups water. Bring just to a boil, then reduce to a simmer and cook, partially covered, until the soup is slightly thickened and the flavors are well blended, about 25 minutes. Remove the thyme sprigs if using.
Add the fish and several grinds of black pepper to the pot. Return to a simmer and continue cooking until the fish is opaque and cooked through, about 2 minutes more.
For the toasts, if making: As you are finishing the soup, heat the oven to broil with the rack 5 to 6 inches from the heat source. In a small saucepan, heat the butter, garlic, thyme, and salt over medium heat, stirring occasionally, until the butter is melted. Reduce to a bare simmer and cook for 1 minute to let the flavors blend. Remove from the heat. Arrange the bread on a baking sheet and brush with the butter mixture. Broil until lightly golden, 2 to 3 minutes.
Gently stir the fennel fronds and celery leaves into the soup. Ladle the soup into bowls. Serve warm, with the toasts if desired.
If you have the French liqueur Pernod on hand, try using it in place of white wine in the soup. Its deep anise notes amp up the fennel flavor of the broth beautifully, adding dimension in a well-balanced way.