Preheat the oven to 350 degrees F (175 degrees C).

For the dough: Combine flour and salt in a large bowl. Cut in shortening until mixture resembles coarse crumbs. Whisk water, egg, and vinegar together in a medium bowl. Stir into flour until mixture forms a ball.

Divide dough into 4 equal balls. Wrap in plastic and refrigerate for 4 hours or overnight. Roll out dough to fit two 9-inch pie pans. Place bottom crusts in 2 pie pans. Roll out and set aside top crusts.

For the filling: Combine apples, rhubarb, strawberries, blueberries, raspberries, and lemon juice in a large bowl. Combine sugar, flour, and tapioca in a medium bowl. Gently toss with fruit mixture.

Divide fruit mixture into 2 prepared pastry-lined pie pans. Cover with top crusts. Trim and crimp edges. Whisk together egg yolk and water in a small bowl. Brush tops of pies with egg wash. Cut a few slits in pie tops to allow steam to vent.