For the Pastry:
- 240 grams (2 cups) all purpose flour
- 3/4 teaspoon salt
- 1/2 teaspoon baking powder
- 226 grams (1 cup) unsalted butter, cold
- 120 grams (1/2 cup) sour cream, cold
For the Filling:
- 2 cups blueberries, fresh or frozen
- 2 tablespoons cornstarch (for fresh berries) or 2 1/2 tablespoons cornstarch (for froze berries)
- 67 grams (1/3 cup) sugar
- 1/8 teaspoon salt (a large pinch)
- 1 tablespoon lemon juice
For the Topping:
- 1 large egg, beaten
- 2 tablespoons white sparkling sugar, for garnish
- To make the pastry: Whisk together the flour, salt, and baking powder. Add the butter. Using a pastry cutter or a fork, work the butter into the flour until the mixture is sandy. There should be pea sized bits of butter in the mixture.
- Add the sour cream and mix until chunks form. Transfer onto a floured surface and knead a few times until it comes together.
- Pat the dough into a rough log and roll into a 8″ x 10″ rectangular. Starting with a short side, fold it thrice like a letter.
- Flip the dough and turn it 90°. Repeat forming into a rectangle and folding in 3. Wrap the dough and chill for at least 30 minutes.
- To make the filling: Place the berries into a saucepan. Whisk sugar and cornstarch together. Pour onto the berries, add salt, and sprinkle with lemon juice. Stir to combine.
- Cook the berries on medium high heat. Stir while simmering. Reduce the heat to medium, stirring constantly. Continue to cook until thickened, for about 5 minutes. Transfer the berries to a bowl and press plastic wrap onto the surface of the filling. Chill until ready to use.
- Preheat the oven to 425F/220C.
- To assemble the pies, roll the dough into a 14″ x 14″ square. Cut out 16 squares about 3 1/2″. Alternatively, use a cookie cutter to cut out the dough.
- Top 8 of the dough squares with a tablespoonful of the filling. Brush some beaten egg on the sides of the squares.
- Cut slits for venting on top of the other 8 squares. A decorative cutter can also be used.
- Top the filled square with the vented dough pieces. Press the edge of the dough with a fork to seal.
- Brush the top of each square with the beaten egg. Sprinkle with sugar.
- Bake for 18-20 minutes, or until lightly golden brown. Remove from the oven and let cool for 20 minutes before serving.
- Refrigerate until firm, around 20 minutes, the dough or the pies when they become too sticky prior to baking.
- Store the pies, lightly wrapped, at room temperature for a couple of days. You can freeze them to store longer.
- If using other berries (e.g. raspberries), you can add or reduce the sugar in the filling.
- After chilling the filling, you can stir it with a spoon to make it easier to work with. Do not heat it up.