Preheat oven to 190ºF .

I make my dough in a food processor, but be careful not to overwork it.

Place the flour and salt into the bowl of the processor, and add the cold butter cut into small squares.

Using the pulse button, blitz the mixture in short bursts so that the flour just lifts and mixes.

Add the egg and water and blitz quickly just until it comes together.

Turn it out onto a board and work it together to form a solid dough.

Wrap it in greaseproof paper (not clingfilm as this will make it wet) and leave the dough to rest in a fridge for at least an hour.  You can leave it overnight if you wish.  The reason you keep it in the fridge is to help the gluten in the flour to relax so that the pastry becomes more elastic and easier to roll.  it also prevents shrinkage later when it goes into the oven.

Roll the pastry out on a floured surface and line your greased chosen tart pan with the pastry.  Press it in and leave excess pastry over the edge of the pan.  Prick the bottom of the pastry with a fork.

Place greaseproof paper over the pastry and cover with baking beans in order to bake blind .  Cook for 20 minutes

Take the tart out of the oven, remove the greaseproof paper and beans and brush the entire tart with an egg wash ( 1 egg whisked up a bit).  Return the tart to the oven for a further 10 minutes.  This lets the pastry cook more and the egg wash forms a waterproof layer on the pastry so that when you put the filling in, it does not soak into the pastry.