2 cups all-purpose flour, plus more if/as needed
1/2 cup cake flour (recommended: Soft As Silk)
3 teaspoons sifted powdered sugar
1/2 cup butter-flavored shortening
1/4 cup salted butter
2 teaspoons vinegar
1/4 cup ice cold water
2 1/2 cups chopped red rhubarb, fresh
2 1/2 cups de-stemmed, washed and cut strawberries (in larger pieces)
1 1/2 cups sugar (1 1/4 cups for high altitude)
2 tablespoons minute tapioca
1 tablespoon all-purpose flour
1/2 teaspoon lemon zest
1/2 teaspoon lemon juice
1/2 teaspoon ground cinnamon
1 teaspoon vanilla extract
3 tablespoons butter, cubed small
1 egg white beaten with 1 teaspoon water
Large granule sugar
Using 2 pastry blenders, blend the flours, sugar, shortening, butter and salt. Whisk the egg, vinegar and water in a 2-cup measure and pour over the dry ingredients incorporating all the liquid without overworking the dough. Toss the additional flour over the ball of dough and chill if possible. Divide the dough into 2 disks. Roll out 1 piece of dough to make a bottom crust. Place into a pie dish. Put dish in refrigerator to chill.
Preheat oven to 425 degrees F.
Mix the rhubarb, strawberries, sugar, tapioca, flour, zest and juice of lemon, dash of cinnamon, and vanilla. Mix well in a large bowl and pour out into chilled crust. Dot the top of the filling with the butter. Brush edges of pie crust with egg white wash. Roll out the other piece of dough and place over filling. Crimp to seal edges. Brush with egg white wash and garnish with large granule sugar. Collar with foil and bake at 425 degrees F for 15 minutes. Decrease temperature to 375 degrees F and bake for an additional 45 to 50 minutes, or until the filling starts bubbling. Higher altitude will take 450 degrees F and 400 degrees F respectively. Also, you can use a pie bird for extra decor. Let chill before serving.