In a bowl, mix together all of the filling ingredients.
Form the dough into a disk, then wrap it tightly in plastic and refrigerate for one hour. You want the butter to be cold so the baked crust turns out flaky.
Add four tablespoons of ice water, and mix with a spoon until it starts coming together into a workable dough. Four tablespoons was just enough for my dough, but if it still looks dry, add one tablespoon of water at a time until you reach the right consistency.
Use a pastry cutter (or a butter knife and your hands) to cut in the cold butter until the mixture has coarse crumbs.
Prepare the crust first, because you'll need to chill it in the refrigerator. Whisk together the flour and salt in a large bowl.