juice 2-3 lemon (about 100ml/3½ fl oz) and 2 tbsp lemon zest
Roll out the pastry on a lightly floured surface to about 2-3mm in thickness, then lift into a tart tin. Press down gently on the bottom and sides, then trim off any excess pastry. Stab a few holes in the bottom with a fork and put back in the fridge for 30 mins.
Heat oven to 160C/140C fan/gas 3. Line the tart with foil and fill with rice or dried beans. Bake for 10 mins, then remove the tart tin from the oven, discard the foil, and bake for another 20 mins until biscuity.
When the pastry is ready, remove it from the oven, pour in the lemon mixture and bake again for 30-35 mins until just set. Leave to cool, then remove the tart from the tin and serve at room temperature or chilled.