Whisk the butter and sugar together in an electric mixer until pale and fluffy then cut open the tea bags and tip in the loose tea leaves ( make sure they are finely ground). Add the lemon zest and salt and whisk to combine.

In a separate bowl, sift together the flour and cornflour then add it to the butter mixture and mix until it forms a dough; shape into a ball.

Roll the dough out on a lightly floured surface to about 5mm thick. Cut into whatever shapes you like and place on two baking trays, prick each biscuit several times with the tines of a fork. Place the trays of biscuits in the freezer for about 15 minutes (or for at least 30 mins in the fridge), while you heat the oven to 170C/325F/gas mark 3.

Bake for 15-20 minutes, until just golden around the edges. Leave to cool on the trays for a couple of minutes then transfer to a wire rack, sprinkle with sugar and leave to cool completely.