To make the shortcrust pastry, place the flour, sugar and butter into the Thermomix bowl and mix on Speed 6, 10 seconds (or until it resembles fine breadcrumbs). Add the iced water and knead for 1 minute on interval speed. Knead the dough into a ball on a lightly floured surface. Wrap in plastic wrap and place it into the fridge for 30 minutes.
Grease a loose-bottomed tart or flan tin (approximately 30cm diameter).
Roll the pastry out between two sheets of baking paper until it is 3mm thick.
Press it down gently into the tin, use a fork to poke shallow holes into the bottom of the pastry and then place it back into the fridge for a further 30 minutes.
Preheat oven to 160 degrees celsius (fan-forced).
Place a sheet of baking paper over the top of the pastry and fill with uncooked rice or baking beads. Cook the pastry for 10 minutes and then remove and discard the weights. Cook for a further 15 minutes or until the pastry is a light golden colour.
Place the eggs, caster sugar, cream and lemon juice into the Thermomix bowl. Mix on Speed 7, 30 seconds. Stir through the lemon zest and pour the mixture into the tin (see recipe tips below).
Cook for 30-35 minutes or until set in the middle. Remove and allow to cool completely and then place into the refrigerator.
Dust with a little icing sugar to serve.