Take the pie dough out of the refrigerator.
Slice the dough in half so you have two equal sized portions.
Generously flour a surface or parchment paper with gluten free flour.
Take one of the pie dough portions and roll it out to a round 1/8 inch thickness about 3 inches wider than your pie plate. So, if your pie plate is 9-inches, you'll want your dough round to be 12 inches in diameter.
Repeat with other pie dough portion, keeping the dough, surface and rolling pin generously floured to make sure it does not stick.
Carefully transfer one of the rolled out pie crusts to a 9-inch pie plate. You should have about 1/2 inch overhang of dough.
Add 1 tablespoon of gluten free flour over the bottom crust to soak up any additional juices from the filling.
Then, pour the strawberry rhubarb pie filling over the bottom crust.
Carefully place the other pie crust on top of the filling.
Roll the edges of the overhanging pie crust under itself until it reaches the pie plate. This will give you a higher crust for crimping.
Crimp the pie crust as desired.
In a small bowl, whisk together egg and water until combined. Brush the egg wash over the pie crust with a pastry brush.
Make a few slits with a knife in the top crust to let air escape during baking.