Sieve the flour mixed with salt.
Break the butter into small pieces with a help of a knife or metal scraper. If some pieces are not broken, then use the hand to break them but take care not to melt the butter too much.
Rub the dough lightly using hands till it resembles breadcrumbs.
Sprinkle water lightly over it and mix the dough to make a lump and knead lightly to make it smooth but don't over knead the dough should just come together smoothly, that's it.
Place the dough for resting for 30 mins probably in the freezer.
Roll the dough with a roller lightly with even strokes.
Cut into desired shape with greased and dusted mould and pierce few holes with the fork to avoid rising and letting out of air.
Place it for baking at 150 degrees for 20-25 mins, at this stage you can also keep some beans in the pie moulds. This is basically called blind baking.
While the pie crust is baking, prepare the lemon filling.
Mix butter and sugar on a frying pan and let it heat on a double boiler.
Blend them and add the egg yolk to it.
In about 7 mins or so, the mixture will begin to thicken and at this stage add the lemon to it.
Stir until it becomes thick and remove from the heat.
Cover the mixture once it comes to room temperature and place in the refrigerator to cool before filling.
When both the crust and filling are cool, pipe the filling in the baked pie crusts.
Decorate as you want, chill before serving.