Place the sourdough starter in a large mixing bowl. (Remember to replenish the starter after you have made your dough, see below. ) Make up to 450g/1lb (2 cups) with water and add the bread flour and salt.
Mix to form a rough ball of slightly sticky dough. The dough does not require kneading just mixing until the flour and water is combined.
Leave in the bowl and loosely cover the bowl. Leave overnight or for about 8-10 hours depending on ambient temperature. The dough will have risen and increased in size.
Knock back the dough and shape into a ball, you can knead lightly if you like but it is not essential. Place smooth side down in a well floured banneton (special basket) or in a 20cm/9in wide mixing bowl, lined with a tea-towel and well floured.
Dust the top of the dough with a little more flour. Cover loosely and leave for a further 4 to 6 hours until risen again.
Turn out of the basket or bowl onto a lightly oiled baking sheet, and slash the top a few times with a very sharp knife. Bake at 220℃ (200℃(fan)/425°F/gas mark 6 for about 50 minutes, until risen and golden. The loaf will sound hollow if you tap it on the bottom when cooked.
Transfer to a wire rack to cool.
Sourdough starter:Keep in the fridge.If it hasn’t been used for a few days try to take out of fridge for about 1-2 hours before required. and add a little flour and water in equal quantities to get it going again.If you don’t use it for a while occasionally discard about ¼ of the starter and replace with fresh flour and water.Replenishing your starter:Replace the starter you have used by adding 75g/3oz (½ cup) flour and 75ml/3floz (½ cup) water. Stir until mixed and return to the refrigerator.I use digital scales so I had my water by weight: 1ml water =1g water.Nutrition information is approximate and is meant as a guideline only.