Preparation Heat the olive oil in a large soup pot over medium heat. Add the leeks and onions and cook, covered, until the vegetables are tender, about 25 minutes. Add the tomato purée, tomatoes, thyme, parsley, bay leaves, wine, fish stock, salt and pepper. Simmer to blend the flavors, 20 minutes. (The soup can be prepared several hours ahead to this point. Return to simmer before proceeding.) Blend the butter and flour together in a bowl and then whisk the mixture into the tomato mixture. Add the mussels and clams in their shells and simmer for 5 minutes. Add the fish and shrimp and simmer until all the shellfish are opened and the fish is done, another 5 minutes. Do not overcook. Ladle the into hot soup plates, discarding any mussels or clams that have not opened. Add a dollop of rouille to each bowl. For the rouille: Mash the garlic, salt, paprika, cayenne to a paste in a mortar with a pestle or with the back of a spoon in a mixing bowl. Let stand 5 minutes. Whisk in the lemon juice and egg yolks. Add the oils, first one drop at a time, then in a thin stream, whisking constantly. The rouille should be the consistency of mayonnaise.