Cut the butter up into pieces. Using a food processor, pulse the flour, butter & salt until just mixed and there are no more large pieces of butter. The mixture should resemble coarse meal. Don't over process or that will warm up the butter and make the dough a bit too sticky to work with.
Add 3 tablespoons of ice water to the dough and pulse until just incorporated. Test to see if the dough will just hold together by squeezing a little bit in your hand. If it's too dry, add another tablespoon or two.
Pour the dough onto a lightly floured surface and knead briefly to make sure the butter is evenly distributed throughout the dough. Form into a ball, wrap in plastic wrap and let chill in the fridge for an hour or until you're ready to use it.