Put the flour, salt, and butter into a large mixing bowl.
With your fingers [preferred] or a pastry blender, press the mixture together until the bits resemble a mix of peas and crumbs.
Sprinkle the 1/2 cup of ice water over the top of the mixture and stir with a fork.
Squeeze the dough together to see if it holds.
By the tablespoon, add ice water, stir, and test again, until a dough is formed.
Divide the dough into two balls, press those into discs, wrap in plastic and refrigerate.
Refrigerate for at least an hour.
The second, extra disc can be reserved for another use or placed, wrapped, in a freezer safe container and frozen.