To make the boudin sausage, in a large saucepan, combine the pork butt, pork liver, water, onions, bell peppers, celery, garlic, 1 teaspoon salt, 1/4 teaspoon cayenne, and 1/4 teaspoon black pepper. Bring the liquid up to a boil and reduce to a simmer. Simmer until the pork and liver are tender, 1 1/4 to 1 1/2 hours.
Remove from the heat and drain, reserving the broth.
Using a meat grinder with a 1/4-inch die or in a food processor, grind the pork mixture, 1/2 cup parsley, and 1/2 cup green onions. Turn the mixture into a mixing bowl. Stir in the rice, remaining salt, cayenne, and black pepper. Add the broth, 1/2 cup at a time, to make a smooth, firm paste, and mix thoroughly. Adjust the seasoning, to taste. Let sit until cool enough to handle.
In a large pot, preheat the vegetable oil to 360 degrees F.
In a shallow bowl, combine the flour with 1 tablespoon of Essence. In another bowl, beat the eggs with the water and 1 teaspoon of Essence to make an egg wash. In a third bowl, season the bread crumbs with the remaining tablespoon of Essence.
Shape the pork and rice mixture into balls the size of walnuts. Dredge the pork balls first in the flour, then dip in the egg wash, letting the excess drip off. Dredge the balls in the seasoned bread crumbs, turning to coat evenly.
Using a slotted spoon, slide the balls in batches into the oil and fry, turning, until golden, about 2 minutes. Remove from the oil and drain on a paper-lined plate. Season lightly with Essence.
To serve, place several boudin balls on a plate and garnish with chopped parsley. Serve with Creole Tartar Sauce on the side.
Yield: about 2 1/2 dozen