This is classic, straight-up rhubarb pie like grandma used to make. No fruity distractions - just sweet-tart rhubarb and tender flaky pastry.Recipe makes one 9½-inch deep-dish, or two standard 8-inch pies.
Prepare Crust: Chill pie plate 30 mins. Roll out 60% of dough; line pie plate with 1½-inch overhang.Freeze 5 mins. Keep remaining dough refrigerated.
Make Filling: Whisk ½ cup sugar and flour. In large bowl, toss rhubarb with remaining sugar-flour mix and tapioca.
Assemble Pie: Sprinkle ½ cupsugar-flour on bottom crust. Add rhubarb filling; dot with butter; sprinkle remaining sugar-flour mix on top.
Top Crust: Roll out top dough; add lattice or solid crust with vents. Fold bottom crust overhang overtop crust; crimp edges to seal. Optional: brush with egg wash.
Bake: Preheat oven to 425°F(218°C). Bake on lowest rack for 15 mins. Reduce heat to 375°F (190°C); bake 30–45 mins until crust is golden and filling bubbles. Cover with foil if crustbrowns too fast.
Cool: Allow pie to cool before serving.
Notes
IMPORTANT: Rhubarb used for filling must be room temperature. DO NOT use chilled rhubarb, or your filling will take too long to cook and your pie shell will burn before the filling is done. Pie Crust PRO TIP: Cut the bottom crust larger enough so that, after you add the top crust, the bottom edge can be folded up over it and sealed, as shown in the image above. In my experience, this significantly cuts down on pie shell leakage around the edges.
Rhubarb Pie Filling Ratios & Guidelines
For each cup of rhubarb, use:
2 tablespoons of flour, or
1 tablespoon of cornstarch, or
1 tablespoon of instant tapioca
For every 5 cups of rhubarb, use:
1 tablespoon of butter
1¼ cups granulated sugar
You can adjust the amount of sugar based on the tartness your personal tastes. Add up to an additional ⅓ cup sugar if your rhubarb is very tart, or if you prefer your pies very sweet.