- 2 tablespoons olive oil
- 1 large yellow onion, finely chopped
- 1 small fennel bulb, finely chopped
- 3 garlic cloves, chopped
- 1 teaspoon dried oregano
- ½ teaspoon red pepper flakes
- 1 teaspoon toasted fennel seeds
- 1 bay leaf
- 1 (28-ounce) can diced tomatoes, juices reserved
- 1 tablespoon tomato paste
- 4 cups seafood stock, plus more as needed
- 1½ pounds white fish such as red snapper or cod, skin and bones removed, cut into 2-inch pieces
- ½ pound medium shrimp, peeled and deveined
- ¼ pound mussels, scrubbed and beards removed
To a large saucepan or Dutch oven set over medium heat, add oil. When oil is shimmering, add onion and fennel and sauté, stirring occasionally with a wooden spoon, until softened, about 7 minutes. Add the garlic and continue to sauté until fragrant, about 1 minute. Add oregano, pepper flakes, fennel seeds, and bay leaf and cook until fragrant, about 1 minute.
Add the tomatoes with the juices, tomato paste, and seafood stock; bring to a simmer. Cook until the stew begins to thicken, about 10 minutes.
Gently stir in the white fish and cook for 5 minutes. Add the shrimp and mussels, gently stirring into the stew. Increase the heat to medium-high and cover the pan. Cook until the mussels open and the shrimp is opaque, about 3 minutes. Remove the lid and discard any unopened mussels. If the stew seems too thick, add additional stock or hot water and thin to desired consistency. Taste and adjust seasoning with salt and pepper.
To serve: Arrange an even portion of fish, shrimp, and mussels in 4 warmed serving bowls. Pour the stew over the seafood.