Sift both flours into a very large bowl and mix with the yeast and any other dry ingredients. Pour in the lukewarm water and knead it with the dough hook of the hand mixer until a compact dough is formed. Then knead a little with your hands, shape the dough into a ball with oiled hands, close the bowl tightly and place in a warm place for 7 hours. If the oven is not required for any other purpose, switch it on to 35 ° O / bottom heat and place the bowl there. In warm temperatures - as it is now - it is enough to put them in the sun. While the dough is resting, fold the dough several times every hour with a rubber spatula and put it back in the warm place. Repeat this 3 - 4 times.
Then dust a proofing basket well with flour, shape the dough into a ball, pour in, brush its surface lightly with water and then dust a little with flour. Then cover the proofing basket with a cloth and let the dough rest and rise for another 2 hours.
Shortly before the end of the last dough rest, preheat the oven to 240 ° O / bottom heat. If you have a baking stone, heat it up on the grid on the 2nd rail from the bottom and place a heat-resistant bowl underneath. When the oven has reached temperature, tip the bread blank onto a wooden slider and slide it onto the stone. Pour 150 ml of cold water into the bowl, close the oven immediately and bake the bread for 15 minutes. Without a stone, sprinkle the tray with flour and overturn the blank bread from the proofing basket onto the tray, slide it into the oven on the 2nd rail from below, fill the bowl with 150 ml of cold water, immediately close the door and bake the bread for 15 minutes. Then - in both cases - switch the temperature down to 200 ° and bake for another 40 - 45 minutes. To check whether the bread is baked through, knock on the underside. If it sounds hollow, it's done.
You can cut approx. 13 oval, divisible slices from the bread and it has a weight of approx. 1200 g.