White sourdough loaf

Method

1. Combine the flour and salt in a mixing bowl. Mix the water and pre-ferment in a large measuring jug. Pour the wet mix into the flour, then use a wooden spoon or dough scraper to bring the dough together, making sure all the flour is worked in. The dough will be quite shaggy.
2. Cover the bowl with an upturned bowl or shower cap and leave for 10 minutes in a warm place. Next, pinch up a small portion of the dough from the side, stretch it up and over, then press it into the other side of the dough. Pinch another piece next to where you grabbed the first and repeat this stretch-and-fold another 6-8 times, working your way around the dough, which will become smooth and more firm as the gluten develops.
3. Rest the dough for 10 minutes more, then repeat the stretch-fold 8-10 times as in step 2. Repeat the whole stretch-fold process twice more (you might need to stretch-and-fold fewer times if the gluten develops too quickly), then after the fourth time, leave the dough in a warm place to rise for 1 hour, lightly covered with an upturned bowl/clean shower cap.
4. Tip out the dough onto a floured work surface and shape into a thick disc. Line a proving basket or colander with a clean tea towel or proving linen (also called a couche). If using a proving basket, you don’t have to line it with a cloth, but you’ll need to generously flour the basket to prevent sticking.
5. Generously flour the proving cloth/basket and put in the dough. Sprinkle more flour on top, then leave in a warm room to prove. It will take 2½-6 hours, depending on the temperature and how active the starter is. The dough is ready when it springs back when gently pressed, looks puffy and has increased in size. (You can also leave it in the fridge to prove slowly overnight.)
6. For the last 30 minutes proving, heat the oven to its highest temperature. Heat a roasting tray
   in the bottom of the oven and a baking sheet on the middle shelf.
7. Remove the hot baking sheet, sprinkle generously with flour, then gently invert the dough from the basket onto the sheet and carefully remove the cloth. Using a baking razor or sharp serrated knife, slash the top of the loaf 4 times.
8. Put the bread in the oven and turn down the temperature to 240°C/ 220°C fan/gas 9. Pour a cupful of water into the bottom tray (this will create steam, which will help the bread rise and form a thick crust). Bake for 30-35 minutes until golden brown. Tap the bottom of the loaf to see if it’s ready – it should sound hollow (if not, bake for 5-10 minutes more). Cool on a wire rack, then slice.