Preheat oven to 400°. Line 2 baking sheets with parchment paper.
Remove one sheet of puff pastry from the refrigerator, leaving one sheet in the refrigerator to stay chilled.
Using a rolling pin, roll the puff pastry into about a 10 x 12 inch rectangle, dust lightly with flour if needed.
Cut the puff pastry into 4 squares using a pizza cutter.
Beat egg in a small bowl.
Spoon strawberry pie filling into the center of each square.
Brush the edges of each puff pastry square with egg wash.
Fold puff pastry over apple filling into a triangle. Use a fork to crimp the edges to seal.
Place turnovers onto a parchment paper lined baking sheet, spacing about 3 inches apart.
Brush all over with egg wash.
Bake for 20 minutes or until golden brown.
Remove from oven to a wire rack and cool slightly.
Repeat with remaining ingredients.
Cool slightly. Dust with powdered sugar if desired.
Serve warm or at room temperature.