How to Make It
Preheat the oven to 325°. In a medium bowl, combine the bread cubes, black olive paste and olive oil. Season with salt and black pepper and toss to coat. Transfer to a rimmed baking sheet and bake for 7 to 9 minutes, until crisp. Let the croutons cool.
Heat the olive oil in a large enameled cast-iron casserole. Add the garlic, onion, celery and carrots and cook over moderate heat, stirring occasionally, until softened, about 15 minutes. Add the saffron and stir for 1 minute. Add the clams, wine and 1 1/2 cups of water and bring to a boil. Cover and cook until the clams start to open, about 5 minutes. Add the mussels, scallops, shrimp and tomatoes and cook until the shrimp are almost white throughout. Add the lobster meat and crushed red pepper and cook until the lobster is warmed through, 1 to 2 minutes. Discard any clams and mussels that do not open.
Pour the stew into a large colander set over a heatproof bowl. Cover to keep warm. Return the broth to the casserole and simmer over moderate heat for 2 minutes. Whisk in the crème fraîche and season with salt and black pepper. Transfer the seafood stew to a large bowl and pour the broth on top. Garnish the stew with the mixed herbs and olive croutons and serve at once.