Directions

1. Chill butter and Crisco until very cold by placing both in the freezer for 15 minutes. Meanwhile, combine egg, water, and vinegar in a small bowl and set aside. Place flour and salt in the bowl of a food processor. Add butter and Crisco to flour and pulse on/off until mixture resembles coarse meal (you can also combine the flour and fats using a pastry blender if you don’t want to drag out your processor – more effort, less clean-up). Scrape mixture into a large bowl, add egg mixture, and stir until combined. Don’t overwork dough.
2. Separate the dough into thirds (If you prefer a more substantial crust, separate in half) and roll into balls. Wrap each ball in plastic wrap and freeze for about 15 to 20 minutes to chill. (If you will be storing the dough in the freezer for a longer period, form dough into a disk and seal in a Ziplock bag. Thaw 15 minutes before using).
3. Meanwhile, make the filling. In a large bowl, combine rhubarb and strawberries and set aside. In a smaller bowl, combine sugars, zest, salt and tapioca. Set aside. (I keep sugar and fruit separate until the last minute to reduce the amount of accumulated juices)
4. Preheat the oven to 400⁰. In between two sheets of waxed paper, roll out the bottom crust, starting at the center and working your way out into a 11” – 12” circle. Once the dough is the correct size, peel off the top layer of waxed paper and, using the bottom sheet, transfer the dough to a 9” pie pan. Flip the dough over, peel off the bottom sheet, and gently press the dough into the pan. Go around the pie pan tucking the dough to make a clean edge. Freeze until second crust is rolled out. Roll out the second crust into a 12” circle between two sheets of waxed paper and transfer to freezer until ready to use.
5. Remove the bottom crust from the freezer. Sprinkle with panko crumbs (this helps avoid a soggy bottom crust). Combine reserved sugar/tapioca mixture with fruit, stir well, and mound filling inside bottom pie crust. Dot filling with bits of unsalted butter. Remove top crust from freezer. Peel off top sheet of waxed paper, flip crust on top of filling, and trim top pie dough so that overhang beyond the pie plate lip is only about 1/2-inch. Tuck rim of dough underneath itself and crimp decoratively. Cut a few decorative vents on top of pie. Transfer pie to a baking sheet and brush egg yolk mixture over dough and sprinkle with sugar. Bake for 20 minutes then reduce temperature to 350⁰ and bake for an additional 30 – 35 minutes, until the pie is golden and the juices bubble visibly. Transfer pie to wire rack to cool. While warm pie is heaven, it’s important to let the pie fully cool giving the tapioca time to do its work or you’ll have a flash flood of filling. When fully cool, the juices gel.