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 cut additional hearts.
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 of filled hearts with egg wash. Top with remaining hearts and press edges firmly to seal. Crimp edges with a fork. Cut a small slit on top of each pie for steam to escape during baking.
07 - Brush tops of pies with egg wash and sprinkle generously with coarse sugar.
08 - Bake for 18 to 22 minutes until tops are golden brown and filling is bubbly. Cool slightly on baking sheet before serving.