Sift the flour into a pile onto your work surface. add the salt and mix through. Add the pieces of butter and rub into the flour with your fingertips.
Make a well in the centre and drop in the egg yolk, quickly work it into the mixture adding a little chilled water to form a smooth crack-free dough.
Roll into a ball, wrap in clingfilm and chill for 30 minutes.
Your pastry is ready to roll out or freeze for up to 3 months.
