Pour the water into a large bowl and stir in the yeast

Add the flour and salt

Mix to a firm dough, then knead lightly for 10 seconds, until evenly mixed

Cover the bowl with cling film and leave at room temperature for 12 hours, until it has doubled in volume; if not, leave until it does

Shape the dough into a stick about 15cm long with tapered ends

Lay diagonally on a tray lined with a silpat or baking paper

Cover with lightly oiled cling film and leave to prove for 30 minutes

Uncover and dust liberally with flour

Press a rolling pin firmly down the centre, so that you almost split the loaf in two, leaving it joined only by a membrane of dough right down the middle

Cover with lightly oiled cling film and leave to prove for 30 minutes

Preheat the oven to 240° Celsius

Bake for 20 minutes, along with a small tray of boiling water on the lowest shelf to make the oven slightly steamy Reduce the heat to 200° Celsius and bake for 20 minutes, until crisp