Roll pie crust into a circle. Spread about half of the pastry cream over the circle. Leave about a 2 inch border. Place sliced strawberries on it in a pattern or regularly. Leave about 1 1/2 inches on the border. Sprinkle with the sugar, and fold up the border around the berries. Beat the egg with a little water. Brush egg wash over the border of the galette and sprinkle with turbinado sugar. Bake in a 350 degree oven for about 1/2 an hour or until the crust is browned. Cool on a wire rack.