This traditional Provençal soup is known for its intense flavor and satisfying nature. Part of the secret behind the taste of this soup is to use very fresh seafood; the other essential component rouille, a saucy garlicky mayonnaise that is the perfect accoutrement.
In a food processor, add bread, garlic paste, chili flakes, egg yolk, 1/4 teaspoon saffron. Blend for 30 seconds, then slowly drizzle in 1 cup of oil. Reserve rouille for soup.
In a large stockpot, heat 1/4 cup oil on medium and add shallot, onion, and a large pinch of salt. Cook until onions are soft, about 5 minutes. Add sliced garlic, lemon zest, and bay leaves and cook an additional minute. Add fennel fronds, tomatoes, potatoes, 3/4 teaspoon saffron, wine, and stock. Bring to a boil, reduce to a simmer, and cook until potatoes are tender, about 10 minutes.
Add thickest pieces of fish to soup first, then add rest, and simmer for 2 minutes. Add mussels and simmer for 3 minutes. Add cockles. Add parsley when all mussels and cockles have opened. (Discard those that have not.) Adjust seasoning.
Add 1/2 cup of soup broth into rouille and mix well. Portion out six servings of soup and add a healthy spoonful of rouille to each serving.
