Preheat oven to 400 F degrees. Line a baking sheet with parchment paper.
In a bowl toss the peaches, blueberries and sugar together.
Start by making the pastry dough. Add the flour and salt to a large bowl and slightly whisk. Cut the butter in pieces and add to the bowl. Using a pastry blender or two knives cut but butter in until the mixture resembles coarse meal. In a small bowl, whisk together the sour cream, lemon juice and water and add this to the butter-flour mixture. Using a wooden spoon or your fingers, mix in the liquid until large lumps form. Pat the lumps into a ball; do not overwork the dough. Cover with plastic wrap and refrigerate for 1 hour.