Step 1: In a large Dutch oven or soup pot over medium heat, heat 1/4 cup olive oil. Add 1 small diced fennel bulb, 1 small chopped leek and 1 large diced white onion. Cook and stir on medium-low until softened, about 10 minutes. Stir in 8 small chopped garlic cloves and cook a couple minutes. Do not brown the vegetables.
Step 2: Add 1 can (28 ounces) tomato puree, 1 quart (32 ounces) seafood stock, 2 tablespoons vermouth, 1/4 cup water, a generous pinch ground saffron and 1/2 teaspoon crushed espelette pepper.
Step 3: Heat to a boil; reduce heat to low, and simmer uncovered, stirring often, about 20 minutes. Puree smooth with an immersion blender or in a blender, working carefully in small batches. (The base can be made several days in advance; refrigerate covered.)
Step 4: Reheat the base, and adjust with up to 1 cup water if the soup is thicker than heavy cream. Stir in 1/2 cup of the rouille (recipe follows). Season with salt (about 1 teaspoon) and a generous 1/4 teaspoon pepper.
Step 5: Add 2 pounds line-caught wild cod fillets, cut into 1-inch pieces. Simmer until fish flakes easily with a fork, about 10 minutes. Use a fork to break up the fish. Season again with more salt and pepper as needed.
Step 6: Serve with remaining rouille and toasted bread.
Step 1: In a bowl, soak 3 or 4 slices 1/2-inch-thick French baguette (or 2 thick slices ciabatta bread) in 2 tablespoons very hot water and 1/3 cup olive oil, until softened.
Step 2: Transfer to a blender. Add 1 jar (12 ounces) roasted red bell peppers, 1/4 teaspoon ground espelette pepper (or 1 small serrano pepper, stemmed, halved, seeded), 3 cloves garlic, 1 teaspoon salt and a pinch of ground saffron (optional). Process until the mixture is a smooth puree.