In a bowl mix rhubarb, strawberries, granulated and brown sugar, corn starch, flour, zest, juice, cinnamon, salt and vanilla, Then set aside.
Preheat the oven to 425 degrees F.
On a floured surface, I divide the dough into two 2 pieces. Then I roll out the dough to fit in the bottom of the pie pan.
Pour in the filling. Cut a couple of tablespoons of butter into small pieces and dot the top of the filling with the butter.
Place a top crust over the filling, crimping the top and bottom crusts together along the edge. Use a sharp knife to cut two vent slits in the center to allow steam to escape as the pie bakes.
So to start the pie's baking time, bake it at 425℉ for 30 minutes. Then reduce the oven temperature to 375℉ and bake for an additional 30 minutes until the filling is bubbling and the crust is nicely browned.