Heat the oven to 180C (160C fan) 350F, Gas 4.
Oil two baking trays.
Weigh the dry ingredients into a bowl and mix to a smooth clean dough with trepid water.
Knead on a floured board until smooth.
Divide into two and roll out thinly on a sheet of foil and covered with cling-film.
Remove the layer of cling-film and use the foil to lift and deposit the thin dough onto the oiled baking tray.
Repeat with other piece of dough.
Mark into squares or fingers using the blade of a sharp knife.
Bake for 10 minutes then open the oven door to allow steam to escape. Reduce the oven temperature to 160C(140C fan) 325F, Gas 3 and bake for a further 10 to 15 minutes until crisp and golden. Watch because this can burn easily.
Cool on a wire rack, break along the marked lines and store in an airtight container.