In a large mixing bowl, swish together salt and flour.

Add butter and rub into flour until you're left with chunks of butter about the size of a dime.

Add water and knead until the dough just holds together.

Turn out onto a work surface, shape into a rough rectangle, and cover with plastic wrap for 10 minutes.

Roll out into a long rectangle, fold up the bottom third, fold down the top third (as if you're folding a letter), and turn 90°. Repeat this rolling and folding 3 more times.

Wrap in plastic and refrigerate for 20 minutes before using.