Combine the flour and salt in a mixing bowl. Add the shortening and work it in with your hands until the mixture resembles coarse meal. Using the tines of a fork, stir as much of the water as you need to bring the dough together, 1 tablespoon at a time. Work it with your hands until you have a smooth ball of dough. Do not over handle the dough. Wrap it in plastic wrap and refrigerate for at least 1 hour. In a large saute pan, over medium heat, melt the butter. When the butter as melted, add the onions, bell peppers, and celery. Season with salt and cayenne. Saute the vegetables until soft, about 6 to 7 minutes. Stir in the paprika. Add the crawfish tails and cook for 5 to 6 minutes, stirring occasionally. Dissolve the flour in the water and add to the crawfish mixture. Stir for 1 to 2 minutes, or until the mixture thickens. Remove from the heat and add the parsley and green onions. Cool to room temperature. Preheat the oven to 375 degrees and lightly oil a baking sheet. Remove the dough from the refrigerator and place it on a lightly floured surface. With a knife, cut the dough into 8 equal portions. Lightly flour each piece. Using your fingers, flatten each piece into a 6-inch round, about 1/4-inch thick. Fill the center of each one with 1/3 cup of the crawfish mixture. Brush the edges of each round with some of the beaten egg. Fold the rounds in 1/2 and crimp the edges with the tines of a fork. Brush the tops of the turnovers with the remaining beaten egg. Place the turnovers on the baking sheet about 1-inch apart. Bake for 45 minutes or until golden brown.