1 pkg frozen 9-inch flat pie crusts, thawed and unrolled
1 pint strawberries, berries cut in half
2 large red rhubarb stalks, cut into 1-inch chunks
1/2 cup sugar, plus 2 Tbsp
1 Tbsp instant tapioca
Zest of 1 lemon
1 tsp vanilla extract
2 eggs, lightly beaten
Place strawberries, rhubarb, 1/2 cup sugar, tapioca, zest, and vanilla in a food processor. Pulse a few times until mixture is blended, but still chunky (makes about 2 cups of filling). Preheat oven to 425°F.
Place pie crusts on floured work surface. Cut into rounds with a floured 3-inch biscuit cutter or the top of a pint glass. On half the rounds, place 1 Tbsp filling. Brush a small amount of egg around the edge of each filled round. Place an unfilled round on top and crimp the edges using a fork or your fingers. Cut a few small slits in the top of each pie. Brush the top of each pie with egg and sprinkle liberally with sugar. Place pies on a baking sheet lined with parchment paper and freeze for 10 minutes. Bake until golden brown, about 20 minutes.