I live in Sumner, WA, which bills itself as the “Rhubarb Pie Capital of the World.” The Washington Rhubarb Growers Association was established here in 1937; it is the largest shipper of fresh and frozen rhubarb in the country, and, according to Wikipedia, half of all US rhubarb production surrounds Sumner in Pierce County. Botanically speaking, rhubarb is a vegetable, not a fruit, and what makes vegetables taste better? Butter and salt, of course.
For Buttered Strawberry Rhubarb Pie, increase cornstarch to 4 tablespoons. Stem and quarter one pound of fresh strawberries and add to the filling with the second addition of rhubarb. Proceed as directed.

Makes one 9-inch pie, serves 8

Ingredients

Pastry:

• 2 1/2 cups (325 grams) all-purpose flour
• 1 teaspoon salt
• 1 teaspoon granulated sugar
• 1/4 cup (48 grams) vegetable shortening at room temperature
• 12 tablespoons (169 grams) cold unsalted butter, cut into 1/2″ cubes
• 1/4-1/2 cup (59 – 118 grams) ice water

Filling:

• 6 tablespoons (85 grams) unsalted butter
• 6 cups (600 grams) fresh or frozen rhubarb, sliced 1/2″ thick (4-6 stalks)
• 3/4 cup (150 grams) granulated sugar
• 2 tablespoons cornstarch
• 1/4 teaspoon kosher salt
• 1 teaspoon cinnamon (optional)
• 2 tablespoons heavy cream, half-and-half, or milk

Instructions

Make the pastry:

1. Place the flour, salt, sugar, and shortening in the bowl of a food processor. Process until shortening is fully incorporated into the flour.

2. Add the cubes of butter and pulse until the mixture forms very coarse crumbs with streaks of butter still visible. Slowly pulse in 1/4 cup of water; the dough should come together without becoming wet or sticky. If it remains crumbly and does not come together, add more water 1 tablespoon at a time.

3. Divide the dough into two balls, one slightly larger than the other, flatten the balls and wrap them separately in plastic. Refrigerate while making the filling.

Make the filling:

4. Melt 4 tablespoons butter in a large skillet, add half the rhubarb and sauté briefly, just until the rhubarb is softened or thawed. Do not let it cook so long that it becomes mushy. Remove from heat.

5. In a medium mixing bowl, combine sugar, cornstarch, salt and cinnamon, if using; stir in the remaining rhubarb. Pour this mixture into the skillet of cooked rhubarb and stir gently to combine. Allow to cool to room temperature.

Assemble the Pie:

6. Preheat oven to 400°F and line a baking sheet with foil and set aside.

7. Remove dough from refrigerator. On a floured surface, roll out the larger disc into a 12” circle and fit it into a 9” pie plate, preferably a glass one. Spoon cooled rhubarb filling into crust. Dot top of filling with remaining 2 tablespoons butter.

8. Roll out the remaining dough into a 10” circle and center it over the rhubarb filling.

Tuck the top crust under the bottom crust. Use a pair of kitchen shears to trim the overhanging edges to 1/2″ beyond the edge of the pie plate, then fold the edges over and crimp the edges together.

9. Brush the top crust evenly with cream. Cut 4 slits into the crust to allow steam to escape during baking. Place the pie in the center of the baking sheet and set it on the bottom rack of the oven.

10. Bake for about 40 minutes, or until the bottom crust is golden brown and filling is bubbling. Allow to cool to room temperature before slicing.