Rhubarb Pie Filling: In a large bowl combine the sugar, tapioca flour, and zest. Add rhubarb and toss to coat.
Assemble: Add one rolled-out pie crust to pie plate. Sprinkle 1 tablespoon coarse sugar over the bottom of the pie crust, to prevent it from getting soggy. Add rhubarb pie filling. top with small pieces of butter dotted over the top of the rhubarb filling. Roll out second pie crust and place on top. Seal the bottom and top crust together. Cut a few slits or a small "X" on the top crust for steam to escape.
Bake at 400 degrees F for about 1 hour (tent the top of the pie loosely with aluminum foil part way through cooking to keep the crust from browning too much).
Cool: Remove from oven and allow to cool for at least 4 hours before cutting. After it cools, refrigerate for up to 4 days.
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Notes
Make Ahead Instructions: Make the Rhubarb Pie filling and store in the fridge for a few days, as needed, before adding to the pie crust and baking. Our pie crusts can also be made ahead and stored in the fridge or freezer.Freezing Instructions: Allow baked pie to cool completely. Cover well with plastic wrap and aluminum foil and freeze for up to 3 months. Thaw completely in the refrigerator before serving.Strawberry Rhubarb Pie: Replace 2 1/2 cups of the rhubarb with chopped strawberries, or try our Strawberry Rhubarb Crisp.