Whisk egg, water, and salt together in a small bowl and set aside.
On a lightly floured surface, roll one piece of dough into a 14-inch circle.
Using a 6-inch diameter bowl or cookie cutter, as many dough rounds as you can, saving the scraps to reroll. Repeat with remaining dough and reroll the scraps to cut additional circles for a total of eight.
If desired, use small cookie cutters to add decorative shapes or patterns into four of the rounds to use as top crusts.
Transfer the remaining rounds of dough into the pie dishes and divide the fruit filling between them.
Working one at a time, use a fingertip to spread some cold water on the top of the lower crust's outside edge. Add the decorated pastry round and trim its perimeter so it extends just beyond pan's top rim. Bend the edge of the top crust down and tuck it into the pie tin so it overlaps the edge of the bottom crust inside the pan. Press gently to seal the two rounds of dough together. Flatten the top crust down and crimp the edge decoratively with your fingers.
If desired, add leftover pastry shapes to the pies, dabbing them with a bit of cold water to help them adhere.
If you haven't cut shapes into the top crusts, use a sharp knife to cut some steam vents. Brush the top crusts lightly with egg wash and sprinkle with coarse sugar.