In a large bowl, whisk flour, salt and sugar.
Add butter and combine with pastry cutter.
Add sour cream. Use a fork to mix into the flour, until combined.
Form the dough into 8 equal balls.
Sprinkle each dough ball with flour and wrap in plastic wrap. Refrigerate at least one hour.
Remove the dough from the fridge and let sit out for a couple of minutes.
Preheat oven to 375F
In a medium bowl, mix together strawberries, sugar, cornstarch and orange juice. Set aside.
On a floured surface, roll each of the dough balls out to a rough circle about 5-6 inches in diameter.
Place the rolled dough onto baking sheets lined with parchment paper.
Place about 1/4 cup of strawberry mixture into the center of each dough circle, leaving a 1-inch lip around the edge (for folding)
Fold the edges of the dough up until they just reach the strawberry mixture. Don't worry if they aren't perfect, it adds character.
Brush the pastry with egg wash.
Bake for 25-40 minutes or until the pastry is golden brown and the filling is bubbly.
Cool completely on wire rack.
Sprinkle with powdered sugar and serve!