Adjust oven rack to the center shelf; preheat oven to 400 degrees F. Line a baking sheet with aluminum foil or parchment paper and set aside.

In a medium mixing bowl, toss together berries, peaches, flour, ginger, brown sugar, and orange zest; set aside. Unfold the puff pastry and, on a lightly floured surface, roll it out into a 10x12-inch rectangle.

Transfer the pastry dough onto the sheet pan and brush edges of dough with some of the egg. Arrange the fruit mixture lengthwise down the center. Fold both sides of the dough lengthwise over the fruit toward the center. Pinch the seam together and tuck it under to seal securely. Pinch the ends to seal, then turn the strudel over so the seam is on the bottom.

Brush the top with the remaining egg and sprinkle sugar over the surface of the dough. With a sharp knife, cut four 1-inch slits down the length of the pastry. Bake 25 to 30 minutes, until pastry is a golden brown and feels crispy to the touch. Remove from oven; cool 15 minutes before serving.