Remove leaves from rhubarb stalks and chop them into 1/2 inch pieces. Place in a large bowl and set aside.
Mix together rhubarb, strawberries, granulated sugar, cornstarch, zest and juice, and salt.
Refrigerate the filling while you make the pie crust.
Preheat oven: 425° F
Place dry ingredients into a food processor. Add butter and shortening one third at a time, pulsing 3 times for each addition, cutting the butter and shortening into the flour until the butter/shortening and flour mixture looks crumbly, with pieces the size of peas.
Add 3 tablespoons of ice water at a time, pulsing to combine until the dough starts to form a ball.
Pour dough onto the counter. Press dough by hand. If it is not holding together, then add 1-2 more tablespoons of ice water until the dough comes together without falling apart.
Press into a log and cut into 2 pieces. Form into disks and wrap well with plastic. Chill for two hours.
Sprinkle flour on the countertop, and roll the dough out from the center. Add flour and turn dough ¼ around each time as you roll. Roll out the dough at least two extra inches than the pie plate. (Use the pie plate to measure).
Transfer the dough to the pie plate by rolling up around the rolling pin.
Fill the pie with the fruit filling.
Roll second piece of dough the same size. Fit it over the filled pie.
Crimp the edges by rolling them up and pressing down with your thumb. Cut three small slices in the center. Brush the surface with vegan wash.
Sprinkle the top crust with sugar, and put into the freezer for 15 minutes.
Bake pie on the middle rack, with a foil-lined baking sheet under pan to catch the drips.
Bake for 15 minutes at 425° F
Turn the temperature down to 375° F for 45-50 minutes.
Check on the pie during the baking process. If it is browning too quickly, place foil around edges of the pie.
When done baking, transfer the pie to a wire rack, and let cool.