In a bowl, mix flour, potato flour, powdered sugar, ground chili, finely chopped ginger, and finely grated lime zest. Cut the butter into small pieces and mix with the flour mixture to form a smooth dough.
From this, form two rolls about 25cm long and 3cm thick and wrap them in cling film, and put them in the fridge for at least 1 hour until they have hardened.
In the meantime line the baking sheet with baking paper. Preheat the oven top/bottom heat to around 200°C.
Cut the rolls of dough into slices and bake in the hot oven for approx. 8 - 9 minutes.
