2 1/2 pounds(1.13 kilograms, about 8 cups) Concord grapes
1 cup(198 grams) granulated sugar
1/4 cup(28 grams) cornstarch
1/2 teaspoonfine sea salt
1 teaspoonvanilla extract
1par-baked pie crust, cooled completely
4large egg whites
1/2 teaspooncream of tartar
1 cup(198 grams) granulated sugar
Pinchfine sea salt
Instructions
Squeeze the pulp from the grapes into a medium pot, releasing the centers from the skins. Reserve the skins in another bowl.
Bring the pulp to a simmer over medium heat and simmer until the grapes have broken down and released their juices, about 10 minutes. Strain the mixture into the bowl with the skins, pressing firmly to extract all of the juice, and discard the seeds that remain in the strainer.
Pulse the mixture to coarsely purée with an immersion blender (or you can do this with a food processor). Let this mixture cool completely.
In a small bowl, whisk the sugar, cornstarch, and salt to combine. Sprinkle this mixture over the cooled grape mixture and stir to combine. Stir in the vanilla.
Heat the oven to 425°F with the rack in the lower third of the oven (preferably with a baking steel or stone on it). Place the cooled par-baked pie crust on a parchment-lined baking sheet.
Transfer the filling to the prepared crust. Transfer the pie to the oven (on top of the baking steel/stone, if using) and bake until the crust is deeply golden brown, 45 to 55 minutes; the filling should visibly be bubbling. If the crust is browning too much, you can tent the edges with foil. Let cool completely.
Shortly before you’re ready to serve the pie, make the meringue. Bring a medium pot with about 2 inches of water to a simmer over medium-low heat. Place a medium bowl on top of the pot and in it whisk the egg whites, cream of tartar, sugar, and salt to combine.
Continue to heat, whisking constantly, until the mixture reaches 160°F on a thermometer. You can use an electric hand mixer to whisk it while it’s heating (faster) or you can transfer the heated mixture to the bowl of an electric mixer fitted with the whip attachment.
Whip the mixture on medium-high speed until it reaches medium peaks, 4 to 5 minutes.
Pile the meringue on top of the cooled pie. Spread the meringue to the edges, but keep it piled a bit higher in the middle. If desired, toast the meringue with a kitchen torch.