01 - Whisk together flour, sugar, and salt in a large bowl. Cut in cold butter using a pastry blender or fingertips until mixture resembles coarse crumbs. Gradually add ice water, mixing just until dough comes together. Divide in half, flatten into discs, wrap in plastic, and refrigerate for 30 minutes.
02 - Combine diced strawberries, sugar, cornstarch, lemon juice, and vanilla extract in a medium bowl. Toss to coat evenly and set aside.
03 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
04 - On a floured surface, roll out one dough disc to 1/8-inch thickness. Cut out 16 heart shapes approximately 3 to 4 inches wide. Re-roll scraps as needed to use all dough.
05 - Place 8 hearts on the prepared baking sheet. Spoon about 1 tablespoon of strawberry filling onto the center of each heart, leaving a border around edges.
06 - Brush edges with egg wash, top with remaining hearts, and press edges firmly to seal. Crimp edges with a fork and cut a small slit on top of each pie to allow steam to escape.
07 - Brush tops with egg wash and sprinkle generously with coarse sugar for a sparkling finish.
08 - Bake for 18 to 22 minutes until golden brown and filling is bubbly. Cool slightly on baking sheet before serving warm or at room temperature.