• This recipe makes a 9-inch, 1-1/2-inch deep pie.

Make the Pie Dough

• Make the pie dough according to this recipe. Wrap the dough in plastic wrap and store in the refrigerator for at least 45 minutes and up to 2 days. While the pie dough is chilling make the crumble.
• Before making the filling roll out and shape the pie dough. Generously flour your work surface. Roll the dough out with a rolling pin to a 12-13-inch circle. Fold the dough in half, and then half again, so it’s in a quarter. Lay it in the pie dish, and gently unfold it. Gently press the dough against the bottom and sides of the pan to remove any air gaps. Trim the edges so they are all about 1-inch past the edge.
• Fold the dough under so the edge of the dough lines up with the rim of the pie plate. Crimp the edges of the dough. Refrigerate the dough in the pie plate for at least 1 hour.

Make the Crumble Topping

• Cut the cold butter into 1/2-inch cubes and place it back in the refrigerator so it stays cold while you prepare the other ingredients.
• Place the flour, and salt in a medium size bowl. Whisk until well combined. Add the butter to the dry ingredients and toss the butter into the flour mixture with your hands until all the butter is well coated.
• Use the pastry blender to cut the butter into the flour mixture, until the mixture resembles clumpy sand, some pieces small, some pieces the size of small lima beans. You can also you use your hands if you don’t have a pastry blender. To mix it with your hands take each piece of butter and smash it flat between your index finger and thumb. Continue to do this until the butter is broken up.
• Add the brown sugar and use your hands to rub the sugar into the butter-flour mixture. The mixture should be crumbly and look like large bread crumbs. Refrigerate the crumble for 60 minutes or place it in the freezer for 30 minutes.
• The crumble can be made up to one week in advance and refrigerated until ready to use.

Make the Rhubarb Filling

• Whisk together the granulated sugar, tapioca flour, cinnamon, and salt in a medium-sized bowl. Set it aside.
• Wash the rhubarb stalks. Place a large mixing bowl on a kitchen scale. Cut off the ends and slice the rhubarb into 1/2-inch pieces. Add pieces to the bowl, weighing as you go, until you reach about 2 pounds. Add the orange juice and vanilla extract and toss the ingredients together.
• Add the sugar tapioca mixture, fold the ingredients together, and let it sit for 30 minutes to start dissolving the tapioca flour and draw some of the liquid from the rhubarb. This step is called maceration and will help insure the tapioca cooks completely.

Preheat the Oven

• While the rhubarb is macerating preheat the oven to 400°F and place a half baking sheet in the oven. The baking sheet catches any drips from the pie. Putting the prepared pie on a hot baking sheet will help ensure a brown bottom crust.

Bake the Pie

• Remove the prepared pie dough from the refrigerator. Spoon the rhubarb into the prepared pie shell. Remove the crumble from the refrigerator and spread it evenly over the rhubarb. Take small handfuls of crumble, lightly press together, then break into irregular chunks as you distribute evenly over the rhubarb.
• Place the pie on top of the hot baking sheet. Bake for 15 minutes, then without opening the oven door, reduce the heat to 350°F and bake for another 30-40 minutes until you see the filling bubbling up around the edges of the pie and occasionally breaking through the crumble in various places. The edges of the pie crust will be golden brown. If at any point the edges of the pie become too dark, place a pie shield over the edges.
• Remove the pie from the oven and place it on a wire cooling rack. Let it cool until room temperature before slicing and serving.

Storing the Pie

• You can store this pie at room temperature in a covered container for up to 2 days, but if it’s warm, I recommend one day. The pie is best eaten while the crumble topping is still a little crisp, and I recommend rewarming the oven instead of a microwave. Store in the refrigerator for up to 3 days covered with foil.