Combine strawberries and sugar in a large saucepan over medium heat. Cook for 10-12 minutes, stirring frequently, until juices release and mixture boils rapidly.

In a small bowl, whisk lemon juice and cornstarch until smooth. Gradually pour into the pan while whisking. Continue cooking for 1-2 minutes until filling thickens and is glossy.

Remove from heat, stir in vanilla, and transfer filling to a bowl. Let cool for 30 minutes.

Preheat oven to 375°F. Prepare pie dish with crust. Whisk egg for egg wash.

Fill pie with cooled strawberry mixture. Cover with second crust, trim edges, and crimp.

Brush top with egg wash and cut small slits for steam. Bake for 40-45 minutes or until golden.

Cool completely, then prepare glaze by mixing powdered sugar, milk, and vanilla. Spread over pie and sprinkle with sanding sugar. Let set before slicing.