To make the cherry filling:

1. Combine the sugar and cornstarch in a small bowl and whisk together until combined. Melt butter in a skillet over medium heat. Add cherries and sugar/cornstarch mixture and stir until combined. Cook cherries until syrupy, bubbling, and tender. Pour into a bowl and set aside to cool.

Make the apple filling:

1. Combine the sugar and cornstarch in a small bowl and whisk together until combined. Melt butter in a skillet over medium heat. Add apples and sugar/cornstarch mixture and stir until combined. Cook apples until syrupy, bubbling, and tender. Pour into a bowl, stir in cinnamon to taste, and set aside to cool.

Make the peach filling:

1. Combine the sugar and cornstarch in a small bowl and whisk together until combined. Melt butter in a skillet over medium heat. Add peaches and sugar/cornstarch mixture and stir until combined. Cook peaches until syrupy, bubbling, and tender. Pour into a bowl. Using a paring knife, scrape the seeds from the vanilla bean into the peach mixture and stir until combined. Set aside to cool.

Build the pies:

1. Line a large rimmed baking sheet with parchment paper. On a lightly floured surface, roll out pastry into a large, thin rectangle. Using a sharp knife, cut dough into evenly sized rectangles (about 6” x 5”). Whisk egg white and water in a small bowl and set aside for egg wash. Place 2-3 tablespoons of fruit mixture in the center of the bottom half of dough. Fold top of rectangle over the fruit mixture so that the two ends meet. Crimp edges with a fork to seal. Using a sharp knife, cut a few slits in top of pie to vent. Place pie on prepared baking sheet and repeat with remaining dough and filling.
2. Brush tops of pies with the egg wash and sprinkle with raw sugar. Chill in the refrigerator for 30 minutes. Preheat oven to 375°. Bake pastries until the tops and bottoms are golden and browned, about 40 minutes. Let cool for 5-10 minutes and then transfer to a wire baking rack to cool completely.
3. Serve warm or at room temperature.