Prepare the dry ingredients: In a large mixing bowl, whisk together the flour, sugar, and salt until evenly combined.
Grate the butter: Use a pastry cutter or grater to grate the butter. Add the butter into the flour mixture until it resembles coarse crumbs with some pea-sized pieces of butter remaining.
Incorporate the sourdough discard: Add the sourdough discard and gently mix with a fork until the dough starts to come together.
Hydrate the dough: Drizzle in 1/4 cup of ice water and mix gently (this is the time I start using my hands to work the dough together). If the dough is still dry or crumbly, add additional ice water 1 tablespoon at a time, mixing after each addition, until the dough holds together when pinched. Be careful not to overwork the dough.
Form and chill the dough: Turn the dough onto a lightly floured surface and bring it together into a cohesive ball. Flatten it into a disc, divide it evenly into two discs, wrap each tightly in plastic wrap, and refrigerate for at least 1 hour (or up to 3 days). If you're only using one pie crust, store the other one in the freezer for up to 3 months.
Roll out the dough: On a lightly floured surface, roll the chilled dough into a 12-inch circle, about 1/8-inch thick. *If the dough is too sticky, add more flour to the surface and the rolling pin. Carefully transfer it to a 9-inch pie dish, gently pressing it into the edges without stretching. Leave an extra inch around the edges and trim any overhang. Move around the pan as you fold the inch of dough underneath. Then crimp or flute the edges as desired. Use a fork to repeatedly pierce the bottom of the pie dough. If the pie you are baking requires an unbaked crust, stop at this step, add the filling, and bake per those instructions. You can freeze the crust for 15-20 minutes to help prevent shrinking before following the pie recipe instructions. Chill before baking: Place the pie crust in the freezer for 15-20 minutes while preheating the oven to 375°F (190°C).
Blind bake the crust: Line the chilled crust with parchment paper and fill it with pie weights or dried beans. Bake for 15 minutes.
Remove weights and finish baking: Carefully remove the parchment paper and pie weights. Return the crust to the oven and bake for an additional 12-15 minutes, or until the crust is golden brown and fully baked.
Cool and use: Allow the crust to cool completely before adding your filling.