Briny shellfish give this quick bouillabaisse its depth of flavor. Basil rouille (a garlicky Provençal mayonnaise) adds vibrancy.

Yield: Makes 6 servings
Active Time: 25 minutes
Total Time: 30 minutes

4 garlic cloves, divided
1/2 cup (packed) fresh basil leaves
1/4 cup mayonnaise
5 tablespoons extra-virgin olive oil, divided
2 anchovy fillets packed in oil, drained
1 tablespoon fresh lemon juice
4 cups (about 1 1/3 pound) cherry tomatoes
1 small fennel bulb, trimmed, halved, thinly sliced
Kosher salt and freshly ground black pepper
1/4 cup dry white wine
1 8-ounce bottle clam juice
3 pounds mixed shellfish (such as littleneck clams, cockles, mussels), scrubbed
2 tablespoons chopped fresh flat-leaf parsley
Crusty bread, sliced (for serving)

Mince or finely grate 2 garlic cloves and transfer to a blender. Add basil, mayonnaise, 3 tablespoons oil, anchovies, and lemon juice. Purée until smooth. Transfer basil rouille to a small bowl, cover, and chill.

Heat remaining 2 tablespoons oil in a large heavy pot over medium-high heat. Add tomatoes and fennel; season with salt and pepper and cook, stirring occasionally, until tomatoes burst, about 10 minutes.

Slice remaining 2 garlic cloves and add to pot. Cook, stirring often, until garlic becomes fragrant, about 1 minute. Pour in wine and cook, stirring often, until almost absorbed, about 1 minute. Add clam juice and 4 cups water and bring to a boil. Add shellfish and cook, covered, until opened (discard any that do not open), about 3 minutes. Stir in parsley. Spread basil rouille on bread and serve alongside.