Freeze the butter for at least 20 minutes, then shred it on a box grater. Set aside.
Put the water in a cup and throw an ice cube in it. Set aside.
In a bowl, combine the flour and salt. Then add the shredded butter and combine with a butter knife or your fingers until there are no piles of loose, dry flour. Try not to work it too hard. It's fine if there are still visible nuggets of butter.
Sprinkle the dough ball with a little iced water at a time until the dough starts to become pliable but not sticky. Use the water to incorporate any remaining dry flour.
If you're ready to roll out the dough, flour a surface, place the dough in the middle, flour a rolling pin, and roll it out from the center.
If you're going to use it later, wrap it tightly in plastic wrap. You can keep it in the fridge for several days or in the freezer for several months, if you wrap it with enough layers. Let it return to room temperature before attempting to roll it out!
If the crust is too crumbly, you can add extra water, but make sure it's at room temp. Sometimes perfect dough is crumbly just because it's too cold, so give it time to warm up.
You can easily patch cracked dough by rolling out a patch and attaching it to the cracked part with a little water. Pinch it together.