Put butter, flour, icing sugar, vanilla pod seeds and salt in food processor.
On medium, whizz to fine breadcrumbs. Reduce and gradually add lightly beaten egg until mixture becomes a firm ball (you may not use all the egg).
I often do the above step by hand. Using my fingers to rub the butter, flour and icing sugar together, then adding the vanilla and salt. Then use a wooden spoon to add egg, and finally patting the whole into a ball with my hands.
Wrap pastry ball in clingfilm and chill in fridge for at least 20 minutes.
15 minutes before you need the pastry, take out of the fridge and rest. Preheat oven to 160℃/300℉. Grease an 18 cm fluted loose-bottomed flan tin, then dust with flour to prevent the pastry sticking.
On a floured surface roll the pastry until 3mm thick and wide enough to cover the flan tin. Use the rolling pin to lift the pastry and put over the tin. Press gently to get the pastry into the fluted sides. Trim excess from top but do NOT trim to the even top of the flan tin. Pastry shrinks and you don't want the filling spilling out over the top later (I have made this mistake).
Prick the pastry all over with a fork. Line with baking paper and fill with baking beans or dried pasta. Bake blind for 20 minutes.
Allow to cool out of the oven for a few minutes before removing baking paper and baking beans. Keep pastry in tin.