Preheat the oven to 425 degrees F.

Combine the strawberries and rhubarb in a bowl. Add the remaining ingredients except for the egg white and mix well.

Remove the dough disks from the refrigerator or freezer and roll the first one out on a cutting board, using lots of flour, until the circle is the size of your pie dish. Drape it over your pie dish. Trim it as needed, and patch it if need be using a bit of water and extra dough scraps.

Add the filling and repeat the process for rolling the second dough disk. Roll it until it is about an inch larger than the pie dish. Drape it over the fruit. Trim the edges and tuck them under.

With a pastry brush, wet between the two crusts and press down with your thumb or a fork to seal it.

Beat the egg white in a bowl and brush the top of the pie. Cut vent holes in the top and on the sides. Place the pie in the oven for 15 minutes, then reduce the heat to 350 degrees F for about 35 minutes more.