In a liquid measuring bowl, whisk together 1/2 cup cold water, 1/4 cup apple cider vinegar, and 1/2 cup ice. Sprinkle 2 tablespoons if the ice water mixture over the flour mixture (from the first step), continuing to use the pastry blender to cut the water into the mixture until it is fully incorporated. Add more of the ice water mixture, 1 tablespoon at a time, using your hands to mix until the dough comes together in a ball with some dry bits remaining. Squeeze and pinch with your fingertips to bring all the dough together, and, if necessary, sprinkle any dry bits with small drops of ice water to combine. Divide the dough into two equal portions. If using a rectangular pie tin, shape one portion into a rough rectangle, and the other into a rough rectangle. If using a regular circular tin, shape both into rough circles. Wrap each portion in plastic, and refrigerate for at least 1 hour, preferably overnight, to give the crust time to mellow. Wrapped tightly, the dough can be refrigerated for 3 days or frozen for 1 month.

Once the dough has chilled overnight and has the texture and consistency of saltwater taffy, it's ready to be rolled. Liberally sprinkle a work surface with flour (see baker's notes). Unwrap the circular portion of dough (but keep the rectangular portion in the fridge!) and place it on the work surface, sprinkling its top with flour. If the dough is hard, let it rest for a few minutes. If the dough seems too sticky at first, add flour liberally. If using a rectangular pie plate, roll the dough out into a rough 5 x 13-inch rectangle about 1/4 inch thick. If using a circular pie plate, roll the dough out to a circle about 11 to 12 inches in diameter and about 1/4 inch thick. In both cases, you can place your pie plate upside down over it to check if the crust is the same size.

Move the dough into the pie plate by folding it into quarters, then moving it into the plate and unfolding it. When the dough is in the plate, press it firmly into the bottom and sides of the plate. Use kitchen shears to trim the excess dough, leaving about 1/4-inch overhang over the pie plate's rim. Cover loosely with plastic wrap and place in the coldest part of the refrigerator while you roll out the second portion of dough.

Re-flour your surface and roll the second disc of dough into a rough rectangle or circle for the lid, following the measurements from the 3rd step. Use a cookie cutter to stamp out designs. Transfer the lid to the refrigerator and chill while making the pie filling.

In a medium bowl, combine 1 1/2 cups fresh blackberries, 1/4 cup cornstarch, and 2 tablespoons granulated sugar. Use your hands to toss the fruit until all the berries are covered with a dust of cornstarch and sugar. Spoon about 1/3 cup passionfruit curd over the mixture, and use a rubber spatula to toss until the fruit is coated with curd. Set aside.

Once the pie has chilled and you're ready to bake, center a rack in the oven and preheat to 350 (F). Prepare a sheet pan by lining with parchment paper.

Once the oven has preheated, remove the pie from the freezer and set on the parchment lined sheet pan. In a small bowl, quickly whisk 1 large egg yolk and 1 teaspoon water together to create the egg wash for the pie. Use a pastry brush to brush the lid and edges with the egg wash; sprinkle immediately with demarara sugar, concentrating the sugar more on the center of the lid than the edges. Transfer to the oven and bake for at least 1 hour, or until the crust has turned golden and the juices are bubbling. If the edges of the pie starts to brown faster than the rest of the lid, cover loosely with aluminum foil.