Preheat oven to 375°F (190°C).
In a bowl, mix flour, salt, and sugar.
Cut in cold butter until mixture resembles coarse crumbs.
Gradually add cold water until dough forms, divide in half, and chill 30 mins.
Roll out dough into rectangles, about 1/8 inch thick.
Cut into equal-sized rectangles (about 4x3 inches).
Place 1–2 tsp strawberry jam in the center of half of the rectangles.
Cover with remaining rectangles and press edges with a fork to seal.
Brush tops with beaten egg and poke a few holes for steam.
Bake 20–25 mins or until golden brown, then cool completely.
Mix powdered sugar, milk, and vanilla for glaze and drizzle over cooled tarts.
