Place flour, sugar and chopped butter in a mixing bowl.
Using fingertips or a food processor, mix the butter into the flour mixture until the mix resembles rough breadcrumbs.
Add enough cold water to mix through and form a smooth dough.
Lightly knead the dough, then wrap it in cling wrap and chill in the refrigerator for 20-30 minutes.
Once chilled, place the dough on a lightly floured board and roll out to about 3mm thick (or desired thickness). If making mini tarts, cut the dough into 12 pieces, roll each into a ball, and roll each ball out with a rolling pin.
Line either a large tart tray or smaller cupcake tray with pastry.
Line each pastry case with baking paper and fill with a layer of rice or baking beans. These will help the pastry cases keep their form during initial baking. Place these in the oven at 180 degrees for 10 minutes, then remove them from the oven, take out the rice/beans and baking paper and blind bake for a further 10 minutes.