Cut butter into chunks, and add to the flour. Toss lightly to coat.
Working quickly, using a pastry blender or your thumb and fingers, cut the butter into the flour mixture until there are only large pea-sized chunks left. You want a few lumps of butter remaining to keep the pastry nice and tender.
Combine ice, water and cider vinegar in a bowl. Sprinkle a few tablespoons of the ice water into the flour and butter mixture, and using a stiff spatula or your hands, mix in well. Continue adding water a tablespoon at a time ( I usually start with about 120g liquid, mix that in, then go from there and add additional liquid as needed) until you have a dough that holds together well, but is not too wet.
Squeeze together with your fingertips to make a homogenous dough. Shape into a rectangle, Rest in the fridge for one hour.
Roll out the dough on a floured surface into a rectangle, fold it in thirds like a letter, then roll again and repeat the folding. Repeat this process one more time. Divide the dough into two pieces, and shape each into a disc by folding the edges under. Rewrap tightly in plastic, and rest for at least two hours, or preferably overnight, before using. Store pie crust in the fridge for up to 3 days, or in the freezer for up to 3 months.
