Dissolve the yeast in some of the water and leave it to stand for a few minutes until it starts to foam.
In a large bowl add the rest of the water, yeast mixture, salt and flour then mix well. Put the dough into a very large plastic container and cover with a lid. Leave at room temperature for two hours.
Knead dough with floured hands on a floured work surface for 30 seconds and shape into a ball. Line a small tin with a large piece of baking paper (it should stand at least 5cm all around).
Put the dough into the prepared tin. Cover dough and let it rise for 1 to 1 1/2 hours.
After about 45 minutes of rising, preheat oven to 230 degrees C. Place a camp oven or dutch oven with a lid in the hot oven and heat for 20 minutes.
Carefully take it from the oven and remove the lid. Place the baking paper with the bread in the hot camp oven and cut off the excess paper (no paper should rise out of the pot).
Cut a cross over the top of the bread with a sharp knife and dust with some flour. Cover and bake 30 minutes. Uncover and bake another 10 minutes. Lift bread out of the camp oven with the baking paper and let cool on wire rack.