In a large bowl, mix together the flour and salt.

Grate cold butter and add it to the flour mixture. Use a pastry cutter, fork, or hands to combine gently until it resembles coarse crumbs.

Add sourdough discard and apple cider vinegar. Mix quickly by hand until dough just comes together, keeping butter cold.

Divide dough into two discs, wrap in parchment or plastic wrap, and refrigerate at least 1 hour.

Lightly flour your surface and roll each disc into circles to fit your pie dish or pie top.

Use immediately or store wrapped in the fridge until ready to bake with your pie filling.