Prepare the pie dough and place in the refrigerator to chill.
Preheat the oven to 425
Chop the rhubarb and strawberries and place in a large mixing bowl. Add in sugar, flour, lemon juice, and a pinch of salt. Mix together and set aside. The strawberries will start to release their juices.
Cut the dough in half and roll out the first half for the bottom crust. Place in a well greased pie pan. Poke the dough with a fork, this helps reduce any air bubbles.
Pour the filling in the bottom crust, and top with cubes of butter.
Roll out the other half of the dough, and cut into approximately half inch wide strips. Then weave the pieces together to form the lattice shape.
Brush the top crust with egg wash, and sprinkle with additional sugar.
Bake at 425 for 15 minutes, then without opening the oven turn down to 350 for an additional 40 minutes, checking after 30.
Serve A La Mode!