Heat the olive oil in a large, heavy bottomed soup pot, add the onions, leeks, and celery, and saute until translucent, about 6 minutes. Add the garlic, tomatoes, saffron, and seasonings. Stir for about 2 minutes, then add the white wine and cook for 4 to 5 minutes, or until almost all the liquid has evaporated, before adding the fish stock. Bring to a boil, then reduce to a simmer and cook for 45 minutes. At the end of 45 minutes, add the potatoes and begin to cook.
While the broth is simmering, make the Peppery Croutons by brushing one side of each French bread slice with olive oil, sprinkle with cracked pepper, and toast in a 300 degree oven until crisp (about 12 minutes).
After the potatoes have simmered for 10 minutes, add the lobster. Return to a boil and cook at a strong simmer for 5 minutes, before adding the fish chunks and the shrimp and cook until the fish is just cooked, but not yet flaking apart. Remove the bay leaves, taste for seasoning, and serve immediately, garnished with the Peppery Croutons.