Ingredients
2 pounds rhubarb, trimmed and cut into 1/2-inch pieces (about 6 1/2 cups)
1 1/3 cups granulated sugar
1/4 cup cornstarch
Pinch of coarse salt
1 teaspoon finely grated lemon zest plus 1 tablespoon fresh lemon juice
All-purpose flour, for work surface
Flaky Piecrust
2 tablespoons unsalted butter, cut into pieces
1 tablespoon heavy cream
1 large egg yolk
Fine sanding sugar, for sprinkling
Preparation
Preheat oven to 375 degrees, with rack in bottom third. Stir together rhubarb, granulated sugar, cornstarch, salt, and lemon zest and juice in a large bowl; set aside.
On a lightly floured surface, roll out 1 piece of dough to a 13-inch round, about 1/8 inch thick. Fit into a 9 1/2-inch deep-dish glass pie plate. Fill with rhubarb mixture, and dot with butter. Refrigerate.
On a lightly floured surface, roll out remaining dough to a 13-inch round. Drape over filling. Trim edge to 1 inch. Fold edge under, and crimp as desired. Make five 2 1/2- to 3-inch slits in crust to vent. Refrigerate 15 minutes.
Whisk cream and egg yolk in a small bowl. Brush over crust. Sprinkle with sanding sugar. Bake until bottom crust is golden and filling is bubbling vigorously, 1 hour 10 minutes to 1 hour 25 minutes. Cover with foil if browning too quickly. Let cool at least 4 hours.
