Mix 500 g flour and salt. Crumble the yeast, mix with 300 ml ice-cold water. Add to the flour and knead everything into a smooth dough. Cover and leave to rise overnight in the fridge.
Preheat oven (electric cooker: 240 °C/circulating air: 220 °C/gas: see manufacturer). Carefully place the dough with the dough card on the floured work surface and do not knead any more. Divide into 2 portions, form each piece into an oblong loaf (approx. 25 cm long) and twist each loaf two or three times.
Put the breads on a baking tray covered with baking paper.
Place a bowl of hot water in the bottom of the oven. Bake the bread for about 15 minutes. Then reduce the oven temperature to 200°C and bake for another 15 minutes.