1. Put the flour and salt in a food processor, add the butter and pulse briefly until the mixture resembles fine breadcrumbs. Add the water and process again until the pastry just starts to come together.
2. Transfer the dough to a lightly floured surface, knead gently and form into a flat disc. Wrap the dough in clingfilm and chill for 20 minutes.
3. Remove the dough from the refrigerator and roll it out on a lightly floured surface.