Add flour, salt, and (optional) sugar to the bowl of a food processor.
Add butter.
Pulse until dry crumbs form.
Add cold water 1 tbsp at a time, pulsing several times after adding, until crumbs become wet. Do not over-process or allow a dough ball to begin to form.
Transfer dough to a lightly floured work surface. Form dough into a disc.
Cover with plastic wrap and refrigerate for at least 1 hour.