Combine the water, salt and TABASCO® Sauce in a boiling pot large enough to accommodate the crawfish. When the water comes to a boil, carefully add the live crawfish. Return to a boil and cook for 3 minutes. Remove from heat, cool, and strain. Cool the crawfish to room temperature.
Peel the tails (you should end up with 2 1/2 pounds peeled crawfish tails), remove the fat from the heads (put in a separate container), and reserve 50 to 60 of the largest heads. Set aside the peeled crawfish and the crawfish fat.
Clean the heads by snipping off the eyes and mouth section, then clean out the shells, rinsing well in cool water. Drain on paper towels and set aside.
For the stock: Crush the remaining heads, the peelings and claws, and put in a large pot with 3 quarts water. Bring to a boil, then reduce the heat and simmer for 30 minutes. Remove from the heat and cool. Strain through a fine-mesh sieve and reserve 6 cups. Set aside.
For the stuffing: Finely chop the crawfish tails or pulse them two to three times in a food processor, and set aside.
Heat the butter in a large saucepan over medium heat. Add the onions, bell peppers, celery, green onions, garlic, and parsley. Cook, stirring, until the vegetables are soft and lightly golden, 5 to 6 minutes.
Add the chopped crawfish tails and cook, stirring, for 3 minutes. Remove from heat. Add the salt and TABASCO® Sauce. Add 1 cup of the bread crumbs and the egg, and stir to mix. The mixture will be thick. Set aside to cool.
Preheat the oven to 375° F. When the crawfish mixture has cooled, stuff each crawfish head with a heaping teaspoon (more or less depending on the size of the head) and arrange them in a shallow baking pan. Generously dust the stuffed crawfish heads with the remaining 1/2 cup bread crumbs, patting the bread crumbs gently into the stuffing.
Bake the heads until the bread crumbs are lightly golden, about 20 minutes. Remove from the oven and set aside.
For the bisque: Combine the oil and flour in a large, heavy pot or Dutch oven over medium heat. Stirring constantly, make a roux the color of peanut butter. Add the onions, bell peppers and garlic. Cook, stirring, until the vegetables are soft, about 5 minutes.
Add the crawfish fat, reserved stock, tomato paste, salt and TABASCO® Sauce and stir to blend. Bring to a boil, then reduce the heat to medium-low and simmer for 1 hour, stirring occasionally.
Add the crawfish tails, the stuffed crawfish heads, green onions and parsley. Cook for 8 minutes, stirring very gently so as not to break up the stuffed heads.
To serve, mound a cup of steamed or boiled white long-grain rice in a soup bowl, ladle some of the bisque over the rice, and include several heads per bowl.
Makes about 8 servings.