for the crusts
2 1/2 cups all purpose flour
1 tablespoon sugar
3/4 teaspoon salt
10 tablespoons (1 1/4 sticks) chilled unsalted butter, cut into 1/2-inch pieces
1/3 cup chilled solid vegetable shortening, diced
6 tablespoons (or more) ice water
For the filling
1/2 cup sugar
2 tablespoons cornstarch
2 tablespoons flour
1 lb (about 3 or 4 stalks) rhubarb, cut into 1/4 inch pieces
4 cups fresh strawberries, washed, hulled and sliced
2 teaspoons cinnamon
Zest from 2 lemons
1 egg for an egg wash
Muscavado or tubinado sugar for the top of the pies
Blend flour, sugar and salt in processor. Add butter and shortening and cut in using on/off turns until mixture resembles coarse meal. Add 6 tablespoons ice water and process until moist clumps form, adding more water by teaspoonfuls if dough is dry. Gather into ball; divide into 2 pieces. Flatten each into disk. Wrap each in plastic; chill 2 hours.
Preheat the oven to 400F. Prepare 6 mini pie dishes (in my case, I have a hamburger bun pan with 6 openings of 4 1/2 inches) with cooking spray.
Mix the sugar, corn starch and flour together. Mix the rhubarb and strawberries into the sugar mixture ensuring everything is coated evenly. Add the cinnamon and lemon zest and mix in well. Set the mixture aside for about 30 minutes.
Roll out and place the dough circles into the baking dishes, taking care not to stretch the dough into the corners but instead pushing on the excess dough from the sides so it falls into the corners. Spoon the fruit mixture evenly into the baking dishes now-lined with the pie dough. Avoid including too much of the liquid into the pies. Using the remainder of the dough, create lattice tops and cover each of the pies. Brush egg wash and sprinkle some sugar on the tops of the pies.
Bake at 400F for 20 minutes then reduce the heat to 350F and bake for another 20 to 25 minutes until the crust is golden brown and the filling is thick and bubbly. Let cool slightly before serving.