Combine the flour, sugar, and salt in a bowl. Add the cold sliced butter and work it into the dough with your hands. Stop when you see nice thin layers of butter in your dough. Add just enough water to keep the dough together when pressed. Wrap with plastic wrap and refrigerate for one hour.

Preheat the oven to 400F.

Roll out the dough on a lightly floured surface. Roll it out into an 11" circle. If the dough starts to get soft, refrigerate for 15-20 minutes until firm. Transfer the circle onto a parchment lined sheet pan. Pour the blueberries into the center of the circle while leaving a 2" border. Sprinkle on the 2 tbsp of sugar.

Fold the border up onto the blueberries creating a rustic crust. Press down gently. Brush the crust with a bit of water and sprinkle on the turbinado sugar. Dot the top of the blueberries with the remaining butter.

Bake for 40 minutes until the crust if golden and the blueberry juices and bubbling.