Sieve the flour from a height on to a clean work surface and sieve the icing
sugar over the top. Using your hands, work the cubes of butter into the flour
and sugar by rubbing your thumbs against your fingers until you end up with a
fine, crumbly mixture. This is the point where you can spike the mixture with
interesting flavours, so mix in your lemon zest.
Add the eggs and milk to the mixture and gently work it together till you have a ball of dough. Flour it lightly. Don’t work the pastry too much at this stage or it will become elastic and chewy, not crumbly and short. Flour your work surface and place the dough on top. Pat it into a flat round, flour it lightly, wrap it in clingfilm and put it into the fridge to rest for at least half an hour.