Make the pie crust according to package directions. Wrap in plastic wrap and chill in the refrigerator for 1 hour.
Preheat the oven to 375 degrees F.
In a small bowl mix together the egg with the cold water to create an egg wash. Set aside.
Divide the dough into 6 even pieces, and roll each into a ball. On a floured work surface roll out each piece of dough, with a rolling pin, into 1/4-inch thick rounds about 3 to 4 inches in diameter. Using a small bowl as a template cut around to form perfect circles.
Break the leftover Salisbury Steak into small pieces and add it to a bowl with the leftover Brown Gravy. Stir to combine.
Put a heaping tablespoon of the meat mixture into the middle of each piece of dough. Brush the edges of the circles with egg wash. Fold the dough over the filling to form a half circle. Press the edges together and seal them again with the tines of a fork to make pretty borders. Brush the tops of the empanadas with the egg wash. Arrange the empanadas on a sheet pan and bake until golden brown, about 15 minutes. Remove the empanadas from the oven to a serving platter and serve.