Ingredients

• 2 tablespoons olive oil
• 1 medium onion, finely chopped
• 4 garlic cloves, chopped
• 1 teaspoon dried basil
• 1 teaspoon dried oregano
• 1/2 teaspoons crushed red pepper flakes
• 1 cup dry white wine
• 1 28-ounce can whole peeled tomatoes
• 2 8-ounce bottles clam juice
• 4 sprigs flat-leaf parsley
• 2 bay leaves
• Kosher salt, freshly ground pepper
• 2 tablespoons olive oil
• 1 medium shallot, finely chopped
• 2 garlic cloves, thinly sliced
• 2 pounds any mix of mussels (debearded), clams, or cockles, scrubbed
• 1/4 cup dry white wine
• 1 pound firm skinless white fish fillets (such as sea bass), cut into 1" pieces
• 1 pound large shrimp, peeled, deveined, tails left intact
• 1/4 cup (1/2 stick) unsalted butter, cut into 1/2" cubes
• Kosher salt, freshly ground pepper
• Flat-leaf parsley leaves (for serving)
• Toasted country bread, rubbed with garlic and olive oil (for serving)

Instructions

1. Heat oil in a large heavy pot over medium heat. Add onion and cook, stirring occasionally, until softened, 8-10 minutes. Add garlic, basil, oregano, and red pepper flakes; stir until fragrant, about 3 minutes. Remove pot from heat and add wine. Return pot to heat, bring to a boil, and cook until wine is reduced by half, about 4 minutes. Add tomatoes with juices, crushing with your hands as you add them.
2. Cook, stirring occasionally, until thickened, 15-20 minutes. Add clam juice, parsley, bay leaves, and 8 cups water; season with salt and pepper. Bring to a boil, reduce heat, and simmer until flavors meld, 10-15 minutes more. Discard parsley sprigs and bay leaves. DO AHEAD: Broth can be made 2 days ahead. Let cool slightly; chill until cold. Cover and keep chilled. Reheat before continuing.
3. For soup: Heat oil in a large heavy pot over medium heat. Add shallot; stir often until softened, about 3 minutes. Add garlic; stir until fragrant, about 1 minute. Remove from heat; add mussels and wine. Set over medium-high heat, cover, and cook, stirring occasionally, until shells open (discard any that do not open), about 4 minutes. Add reserved broth; bring to a simmer. Add fish and shrimp. Cover; cook just until opaque, about 4 minutes. Stir in butter; season with salt and pepper. Divide among bowls; top with parsley. Serve with toast.
4. Heat oil in a large heavy pot over medium heat. Add shallot; stir often until softened, about 3 minutes. Add garlic; stir until fragrant, about 1 minute. Remove from heat; add mussels and wine. Set over medium-high heat, cover, and cook, stirring occasionally, until shells open (discard any that do not open), about 4 minutes.
5. Add reserved broth; bring to a simmer. Add fish and shrimp. Cover; cook just until opaque, about 4 minutes. Stir in butter; season with salt and pepper. Divide among bowls; top with parsley. Serve with toast.