Thus began my cherry pie experimentation. I wanted to change up the starch so the filling would be clear, tasteless, and perfectly smooth.
Having made pies with both flour and cornstarch in the past, I rejected those; the flour has a pasty flavor and the cornstarch isn't quite as clear as I was looking for (though it's close and it's definitely my second favorite thickener, use 3 tablespoons for 2 pounds of sour cherries).
But two starches I hadn't tried were potato starch and tapioca starch (a.k.a tapioca flour). I had read glowing reports about their marvelous thickening power in fruit pies. I was gravely disappointed in both. The tapioca was cloudy and had a bitter aftertaste (we ate it anyway). The potato starch was also cloudy, pasty, and gave me cherry soup in a crust (we ate part of it then had to toss it after the whole pie kind of dissolved into an unappetizing mush). I read somewhere that potato starch can break down when boiled and perhaps that happened to me.
One thing I found interesting was that tapioca starch was not just ground up instant tapioca pearls. Tapioca pearls, the kind used to make pudding, are treated to become more stable (Cooks Illustrated has more info on this). The starch is a less processed product, but also less predictable in its thickening power. This might be why I had such problems with my pie, whereas I've heard reports that other people's pies are just swell using the stuff. You can't count on it.
In the end, what I decided to do was to grind up 2 tablespoons instant tapioca in a coffee grinder until it turned to powder (I had tried it in the food processor and while it did make the pearls smaller, it didn't turn them to powder the way the grinder did). Then I mixed the powder into the cherries.
The result? The filling is clear, flavorless, glossy, and thickened without being firmly set or gloppy (you could use a little more if you like your pie completely set). I also used a teensy bit of lard in the crust to make it extra flaky.
In a word: Yum.
Next project up: making a cordial out of the leftover sour cherries. I'm going to mash them up (with pits), add booze (will try it with vodka, Bourbon, and brandy), and let it sit for a few months. Will report back in December.
New Twice-Baked Sour Cherry Pie
Time: 1 hour 45 minutes, plus chilling time
For the crust:
1 3/4 cups plus 2 tablespoons all-purpose flour
3/8 teaspoon kosher salt
13 tablespoons unsalted butter, chilled and cut into pieces
2 tablespoons lard, chilled
3 to 6 tablespoons ice water
For the filling:
1 cup sugar (or more if you like a sweeter pie)
2 to 3 tablespoons instant tapioca (more if you like it very set, less if you don't mind a little thickened juice)
1/4 teaspoon ground cinnamon
2 pounds sour cherries (about 6 cups), rinsed and pitted
1 tablespoon kirsch or brandy
3 tablespoons heavy cream
Demerara sugar, for sprinkling
1. First make the dough, in the bowl of a food processor pulse together flour and salt just to combine. Add butter and lard and pulse until chickpea-sized pieces form. Add the water one tablespoon at a time and pulse until mixture just comes together. Pat the dough into 2 discs, one using two-thirds of the dough, the other using one-third of the dough (weigh it if you have a kitchen scale, one disc should be 12 ounces, the other 6 ounces). Wrap the discs in plastic and refrigerate at least 1 hour (and up to 3 days), before rolling out and baking.
2. Preheat the oven to 425° F. Place the large disc on a lightly floured surface and roll it into a 12-inch circle, about 3/8-inch thick. Transfer the dough to a 9-inch pie plate. Line the dough with foil and weigh it down with pie weights. Bake until the crust is light golden brown, about 30 minutes.
3. While the piecrust is baking, prepare the filling. Using a coffee or spice grinder, grind the tapioca to a fine powder. In a small bowl, combine the tapioca with the sugar and cinnamon. Place the cherries in a bowl and add the sugar and tapioca mixture. Drizzle in kirsch or brandy and toss gently to combine.
4. When the pie crust is ready, transfer it to a wire rack to cool slightly and reduce the temperature to 375° F. Remove the foil and pie weights and scrape the cherry filling into the pie crust.
5. Place the smaller disc of dough on a lightly floured surface and roll it 3/8-inch thick. Use a round cookie cutter (or several round cookie cutters of different sizes) to cut out circles of dough. Arrange the dough circles on top of the cherry filling.
6. Brush the dough circles with cream and sprinkle the top of the pie generously with demerara sugar. Bake until the crust is dark golden brown and the filling begins to bubble, 50 minutes to 1 hour. Transfer the pie to a wire rack to cool for at least 2 hours, allowing the filling to set up before serving.
Yield: 8 servings