Put the stock in a large, heavy pot on medium heat and bring to a gentle boil. Add the saffron, leeks, tomatoes, orange juice, orange zest, fennel, garlic, and parsley. Season with salt and pepper. Turn down to a simmer and cook the liquid for 6 minutes.
Season the fish with salt and pepper. Add the fish to the pot. Cook for 12 minutes, or until the fish is flaky. Remove the fish and set aside.
In a large saucepan, over low heat, combine 1/4 cup of the Aïoli and the egg yolks, together. Whisk until smooth. Slowly whisk into the fish liquid. Continue to cook until the liquid starts to thicken, 2 to 3 minutes. Remove from the heat. To serve, place the croutons in the center of each bowl. Ladle the sauce over the bread. Lay a couple pieces of fish on top of the crouton. Serve the remaining Aïoli and Rouille in sauce boats to the side of the La Bourride.
Yield: 6 to 8 servings