Preheat the oven to 200 degrees Celsius / 400 degrees Fahrenheit
Make your shortcrust pastry by sieving the flour and a large pinch of sea salt into a bowl and adding the cold butter in small chunks.
Rub the butter and flour together using your fingertips together until it looks like breadcrumbs, with no visible big bits of butter that aren't rubbed into the flour. Do this quickly, as we don't want to overwork the mixture and for the butte to heat up and melt.
In a small glass, mix the egg yolk with the water and begin adding it tablespoon by tablespoon to the flour/butter mixture.
Let it start to come together gradually, and keep adding tablespoons of the egg/water until you have a ball of pastry dough that has a slight sheen to it and any dry crumbs have been incorporated. It shouldn't be wet or soft.
Roll the pastry out into a large circle and line a tart tin with it, leaving some overhang around the edges in case it contracts when baking. Prick the base of the shortcrust pastry a few times all over it with a fork.
Line the inside of the pastry case with a baking paper cartouche and fill with baking beads (or use uncooked rice if you don't have any). This stops the pastry from rising.
Blind bake the shortcrust pastry case on an oven tray for 20 minutes, then remove the baking beads and put the pastry case back in the oven for a further 5-10 minutes until it is cooked through and a light golden brown. The base of the pastry case should feel dry and not spongey to touch.
Using a vegetable peeler, shave off the excess shortcrust pastry from the edge of the case.