Preheat your oven to 400°F (200°C).

In a medium bowl, combine the sliced strawberries, sugar, and vanilla extract. Let this mixture sit for about 10 minutes.

On a lightly floured surface, roll out the puff pastry sheets to your desired thickness.

Cut the rolled pastries into squares or rectangles, about 4x4 inches.

Place a spoonful of the strawberry mixture in the center of each pastry square.

Fold the pastry over the filling to create a triangle or rectangle, then press the edges firmly to seal.

Beat the egg and brush the mixture over the top of each pastry.

Place the pastries on a baking sheet lined with parchment paper and bake for 20 minutes or until puffed and golden brown.

Remove from the oven and let cool slightly before serving.