sweet pastry staple recipe (paté sablée)

this is my staple sweet pastry adapted from Christine Manfield's paté sablée. this is a small quantity, enough for a 22cm tart case (too much left over would be a bad thing), but this recipe can easily be tripled without adjustment for a large dessert

100g flour (I use plain cake flour but it can contain up to 30% tipo "00" without the sides caving in)
50g butter
40g icing sugar
1 egg, beaten
a small grating of lemon zest
a drop of vanilla essence
a pinch of salt if using unsalted butter

rub the butter and flour together then add the sugar and rub to a fine crumbly texture, like sand (sablée).
add the lemon, vanilla and salt if using and mix a little.
gradually add egg by the teaspoonful, mixing lightly in between to check for formation and stickiness (probably not more than 3 teaspoons will be necessary).
bring the dough together and knead gently only for a couple of folds - the less handling the better.
refrigerate the dough for about 20 minutes.
butter the flan tin or tart case then press the pastry across the bottom and sides in pieces or slices until you have an even shell with a little overhang.
put the tin back in the fridge while preheating the oven to 160°c, this will help stop the pastry shrinking.
trim any overhang just before baking, then blind bake the pastry case with weights for 15-25 minutes depending on whether it will be used for a baked filling.