Some recipes just come to you. I've been reading Anne Dimock's book Humble Pie and so I had a hankering to bake. Her special pie is rhubarb and I knew there was some in the refrigerator. It was not quite enough for her pie but there were local red plums in the drawer and Alex suggested that I combine the two. It was almost the perfect pie. sweet and tart, the filling somehow somehow creamy and tangy without a drop of dairy inside. Alex ate his with vanilla ice cream and Amaya and I enjoyed ours straight up.
Makes one 9-inch pie
The amount of fruit below is not exact, it depends on what you have on hand. You are going for 5 cups total and the ratio of plum to rhubarb is fluid. Ours was slightly more rhubarb, almost 3 cups so we had a pie that quivered on balance between sweet and tart but if you prefer a sweeter pie you can skew your ratio more towards the plums.
2 prepared piecrusts: we use an all butter crust, recipe in Maximum Flavor
2-3 cups sliced rhubarb
2-3 cups diced plums, use firm, tender plums, not ones that are overly soft and mealy
1 1/4 cups (250 grams) sugar
1/4 cup (28 grams) cornstarch
2 tablespoons (12 grams) tapioca starch
1/8 teaspoon (0.75 grams) fine sea salt
milk for brushing the top of the pie
1 1/2 tablespoons raw sugar for the top of the pie
Preheat oven to 425°F
Put the rhubarb and plums in a medium bowl and then add the sugar, cornstarch, tapioca starch, and salt. Mix gently with a rubber spatula to blend. Set aside while you roll out the piecrust.
Line the bottom of a 9-inch pie pan, preferably heatproof glass, with one pie crust. Gently stir the fruit again and pour it into the bottom crust being sure to get all of the juice as well. Roll out the second piecrust and lay it over the top. Trim the crust so that it has a 1 1/2-inch overhang and then fold it over the edges of the bottom crust and crimp it closed all the way around the circumference. Use a small, sharp knife to cut a few vent holes in the pie. Brush the top crust with milk and scatter the raw sugar evenly over it. Bake for 20 minutes and then, without opening the oven door, reduce the heat to 350°F and bake for another 50 minutes. The pie should be a deep golden brown on the top and on the bottom. (Here's where the glass pie pan is handy, it's how I learned that our pies need to cook for much longer than I thought.)
Let the pie cool completely at room temperature.