Heat olive oil in a large stockpot over medium heat. Add chopped fennel bulb, sliced leeks (white part only), and minced garlic. Sauté for 5–7 minutes until softened and fragrant.

Add Tomato Base

Stir in diced tomatoes (fresh or canned) and cook for another 5 minutes until the tomatoes break down slightly and start to integrate with the aromatics.

Add Liquids and Simmer

Pour in 6 cups of fish stock or water with fish bouillon. Add a bouquet garni (parsley, thyme, bay leaf tied together), salt, pepper, orange zest, and a pinch of saffron threads. Bring to a boil, then reduce to a simmer and let cook for 30–40 minutes to develop flavor.

Prepare the Seafood

Clean Shellfish

Scrub the mussels and clams thoroughly under cold water, removing beards from mussels and discarding any open ones that don’t close when tapped. Rinse oysters and set aside. Peel and devein the shrimp, cleaning the scallops and cutting larger ones into halves if needed.

Add Firm Fish

Cut firm white fish (such as cod, halibut or snapper) into chunks. Add fish to the simmering broth and cook for 5–8 minutes or just until cooked through.

Add Shellfish and Finish Cooking

Add mussels, clams, oysters, scallops, and shrimp to the broth. Cover the pot and allow the shellfish to steam and open, about 5–7 minutes. Discard any clams or mussels that don’t open.

Make Rouille Sauce

Create Rouille

In a food processor, blend together 2 garlic cloves, 1 small boiled potato, 1 egg yolk, 1 roasted red pepper, and 1 teaspoon Dijon mustard. While blending, slowly drizzle in olive oil to form a smooth paste. Add salt, pepper, and cayenne pepper or saffron to taste.

Prepare the Croutons

Toast Baguette Slices

Slice a baguette into thin rounds, drizzle with olive oil, and toast in a 375°F (190°C) oven until golden and crisp, about 8–10 minutes.

Serving

Assemble and Serve

Ladle the bouillabaisse with a generous mix of broth and seafood into large bowls. Serve with toasted croutons spread with rouille on the side or placed directly atop the soup. Optionally, garnish with chopped parsley or fresh fennel fronds.