Make the pie crust: Whisk together flour and salt. Cut in cold butter until mixture resembles coarse crumbs. Gradually add ice water, mixing until dough just comes together.
Chill the dough for at least 30 minutes.
Prepare the filling: In a bowl, combine blueberries, sugar, cornstarch, and lemon juice.
Roll out the dough and cut out circles. Fill each circle with blueberry filling, fold over to form a half-moon shape, and crimp the edges.
Bake at 375°F (190°C) for 25 minutes, or until golden brown.