The sourdough starter must be prepared two days before making the bread: mix in a bowl the yeast, 5 dl of lukewarm water, and 300 g of flour. Let it rest in a cool place (12°C) for 48 hours. After this time, add to the starter the salt, oil, 4 dl of lukewarm water, and 1 kg of flour. Mix and knead the dough, incorporating the remaining flour. The dough should be firm. Cover with a cloth and let it rise for 3 hours. Divide the dough in half. Shape two large oval loaves. Cover them and let them rise again for 1 hour 30 minutes. Before baking in a wood-fired oven, make deep cuts on the top of the loaves and brush them with lukewarm water.