2tablespoonsflour,plus additional for work surface
1egg yolk,beaten with 2 teaspoons water (for egg wash)
Preheat oven to 375. Line a baking sheet with parchment paper.Combine blueberries, sugar, flour, and lemon juice in a bowl. Roll out each sheet of pie dough on a lightly floured surface. Cut each sheet into 6 squares, roughly 4 by 4 inches, for a total of 12 squares of dough. Discard scraps. Spoon a mounded tablespoon of the blueberries onto each dough square. Using your finger, lightly brush the border of each square with water. Fold in half and seal with a fork. Transfer to prepared baking sheet. Cut slits in the top of each pie and brush lightly with egg wash. Sprinkle with additional sugar. Bake 25-30 minutes, until pies are golden brown and filling is bubbling.