Step 1

In a large bowl, whisk together the flour and salt. Add the cubed butter, tossing the cubes through the flour until each individual piece is well coated. ‘Cut’ the butter into the flour by pressing the pieces between your fingers, flattening the cubes into big shards. As you work, continue to toss the butter through the flour, recoating the shingled pieces. Continue cutting the butter into the flour just until the pieces of butter are about the size of peas.

Step 2

Make a well in the center of the flour mixture. Add the amount of ice water listed in the recipe to the well, but have more on hand. Use a tossing motion with your hands to start to mix the two together (this begins to combine them without creating too much gluten). As it begins to become hydrated, you can start to use more of a kneading motion. Add more water about 1 tablespoon at a time until the dough is properly hydrated: it should be uniformly combined and hold together easily, but it won’t look totally smooth. Dough that is too dry may have sort of a “dusty” appearance, or pockets of un-hydrated flour. It will not hold together and will appear crumbly. Dough that is too wet will feel sticky or tacky to the touch, and is often smoother and/or lighter in color.

Step 3

Form the dough into a disk and wrap tightly in plastic wrap. Refrigerate for at least 30 minutes or up to 2 days before using.

Step 4

To roll out the dough, lightly dust a work surface with flour, and lightly dust a rolling pin, if desired. Roll out the dough to about 1/4 inch thick, rotating it as you work to help prevent it from sticking. To transfer the dough to the pan, gently roll it up, wrapping it around the pin, then unfurl it into a deep-dish pie plate.

Step 5

Use scissors to trim away the excess dough, leaving about 1/2 inch excess all the way around the outside edge of the pie plate. Tuck this excess dough under, pressing gently to make it flush with the edge of the pie plate. Crimp the edges as desired, and dock the base and sides of the crust with a fork. Cover with plastic wrap and chill for at least 30 minutes and up to overnight.

Step 6

Par-bake the dough: Arrange a rack in the middle of the oven and heat the oven to 425ºF. Cut a square of parchment paper slightly larger than the diameter of a pie plate, and press it into the base of the pie plate. Fill with pie weights to the top inner rim of the pie plate. Bake until the edges begin to lightly brown, 15-17 minutes. Remove the parchment paper and pie weights, and return to the oven until the lower portion of the crust appears dry and set, 2-3 minutes more. Set aside to cool completely while you make the filling.

Step 7

In a large bowl, toss the berries with the lemon juice and granulated sugar. Let macerate for at least 1 hour, or up to 3 hours; toss the berries occasionally during the first 15 to 20 minutes to help ensure they’re all getting evenly juicy.

Step 8

Biscuit Topping: Meanwhile, in a medium bowl, whisk the flour, sugar, baking powder, baking soda, and salt to combine. Add the butter and mix with your hands or a pastry cutter until the mixture resembles coarse meal.

Step 9

In a container with a spout (such as a liquid measuring cup), whisk the buttermilk, egg, and vanilla until well combined. Make a well in the center of the flour mixture and pour the buttermilk mixture into it. Use a silicone spatula to stir the mixture until it comes together into a dough. Refrigerate until ready to use.

Step 10

Place a colander over a medium pot and pour the berries into it. Press down gently on the berries—you don’t want to smoosh the fruit too much, but you want to get all of the juices that you can into the pot. Transfer the berries to a bowl.

Step 11

Set the pot over medium heat, bring the juices to a simmer, and simmer until they have reduced to 1/4 cup. The amount of time this takes will depend on how much juice your berries yielded. Remove from the heat.

Step 12

Meanwhile, preheat the oven to 375°F with a rack in the lower third (preferably with a Baking Steel or stone on it).

Step 13

In a small bowl, mix the brown sugar, flour, cinnamon, salt, and vanilla bean seeds, if using (if using extract, you will add it later). Use your fingers to mix the ingredients until they’re uniformly combined.

Step 14

Toss the brown sugar mixture with the berries to combine well, then pour the reduced juices over and toss again. If using vanilla extract, add it and toss to combine.

Step 15

Place the cooled crust on a parchment-lined baking sheet. Add the filling to the crust and spread into an even layer. Crumble the biscuit topping evenly over the top of the pie, leaving some of the filling exposed at the edges. Sprinkle with turbinado or coarse sugar.

Step 16

Transfer the pie to the oven and bake until the crust is deeply golden brown and the filling is bubbling around the edges and/or a tester inserted into the center of the biscuit topping comes out clean, 35 to 40 minutes. Cool completely before slicing and serving.