Prepare rouille: Using a long handled fork, char the pepper on all sides over a gas flame or charcoal grill. When the skin bubbles and blackens, remove from the heat. When cool enough to handle, scrape away the charred skin, remove the stem, and scrape away the seeds.

In a small bowl, let the bread slice soak up the vinegar, then squeeze out the vinegar.

In a food processor fitted with the metal blade, combine the roasted pepper, bread, egg yolks, garlic, hot-pepper flakes, salt, and pepper. Pulse the mixture on and off until smooth. With the machine running, gradually add the olive oil in a slow steady stream and process until the mixture is the consistency of thick mayonnaise. Add the boiling water to lighten the mixture. Scrape the mixture into a bowl, cover, and set aside. (The rouille can be prepared 1 day ahead and refrigerated. Bring to room temperature before use.)

Prepare the croutons: Preheat the oven to 350°F. Place the bread on a baking sheet and bake 10 to 15 minutes until golden brown. Set the croutons aside.

Prepare the stock: Rinse the fish bones well under cold running water, checking to be sure the gills have been removed.

Place the fish bones and all the remaining ingredients in a large soup kettle, and add enough cold water to cover. Bring the stock to a boil over high heat. Reduce the heat to low and simmer for 1 hour. Remove from the heat and cool.

Line a strainer or colander with a damp kitchen towel or a double thickness of damp cheesecloth and place it over a clean pot. Ladle the stock into the strainer, then add the bones and vegetables. Let the stock drain for 15 minutes. Do not press out the juices. Set aside. (Makes about 2½ quarts; the stock can be prepared up to 2 days ahead if kept covered and refrigerated, or frozen for up to 1 month.)

Prepare the soup: In a large nonreactive stock pot. heat the olive oil over medium heat. Add the onion and sauté until wilted and translucent, about 10 minutes. Add the tomatoes and their juice and simmer for 10 minutes. Add the stock, bring to a simmer, and cook for 5 minutes. Add the carrots, leeks, and celery and simmer for 10 minutes or until the vegetables are tender but not overcooked.

Stir in the parsley, basil, thyme. tarragon, saffron, and optional Ricard and simmer for another 10 minutes. Season with salt and pepper.

Ladle the soup into warm soup plates. Spread some of the rouille on top of a crouton and float on top of the soup. Accompany with grated Parmesan cheese and additional croutons and rouille.