01 - Preheat the oven to 375°F. Line a baking sheet with parchment paper to prevent sticking.
02 - In a small mixing bowl, combine the finely diced strawberries, granulated sugar, cornstarch, lemon juice, and vanilla extract. Stir thoroughly and set aside to macerate for 5 minutes.
03 - On a lightly floured work surface, carefully unroll the thawed pie dough sheets. Using a heart-shaped cookie cutter, approximately 3 to 4 inches wide, cut out a total of 16 heart shapes.
04 - Place 8 of the prepared heart shapes onto the parchment-lined baking sheet. Spoon about 1 tablespoon of the strawberry filling onto the center of each dough heart, ensuring a clean border around the edges.
05 - Lightly brush the edges of the filled dough hearts with the beaten egg. Carefully place the remaining 8 heart shapes on top of the filled halves. Gently press the edges together to seal, then use the tines of a fork to crimp the seams securely.
06 - Create a small vent on the top of each hand pie by cutting a small slit or poking a hole, allowing steam to escape during baking. Brush the tops of the pies with additional egg wash and, if desired, sprinkle with coarse sugar.
07 - Bake for 18 to 22 minutes, or until the pastry is golden brown and the filling is visibly bubbly. Allow the hand pies to cool on the baking sheet for at least 10 minutes before serving.