For the crawfish stock: Remove the tails from the 5 pounds of boiled crawfish and peel, reserving the tail meat for the bisque and the peelings for the stock. Pinch off the claws and reserve. Put the tail peelings and claws in a stockpot and cover with the water. Bring to a boil. Simmer, uncovered for 45 minutes. Drain. You should have about 3 quarts of stock. Let the stock cool.
For the bisque: Combine the oil and flour in a large cast iron or enameled cast iron Dutch oven over medium heat. Stirring slowly and constantly for 20 to 25 minutes, make a medium brown roux, the color of peanut butter. Add 3 cups of the onions, 1 1/2 cups bell peppers, and 1 1/2 cups celery. Season with salt, pepper, cayenne, and bay leaf. Cook, stirring often, for 6 to 7 minutes, or until the vegetables are soft. Add the reserved crawfish tails. Stir and cook for 3 to 4 minutes. Add the crawfish stock and bring to a boil. Simmer over medium heat, uncovered, for about 1 hour and 15 minutes. Add 1/4 cup of the green onions and the parsley.
For the boulettes: In a food processor with a metal blade, combine the remaining onions, peppers, celery, garlic, 1 pound peeled crawfish tails, bread pieces and egg together. Pulse the mixture a few times to finely chop the mixture. *Do not puree. Transfer the mixture to a mixing bowl and stir in the remaining green onions and parsley. Season with salt, pepper, and cayenne. Shape the mixture into small balls, about 1 tablespoon each. Season the bread crumbs with the Rustic Rub. Roll the balls in the seasoned bread crumbs. When the oil has reached 360 degrees F, deep-fry the boulettes until golden brown, about 2 minutes. Remove the boulettes from the oil and drain on a paper-lined plate. Season with Rustic Rub. Garnish each soup with a couple of the boulettes.
Combine all ingredients and store in an air-tight container.