Measure 50g of active starter into a bowl.
Add 350g water to it and mix well.
Add 500g bread flour and 9g of good sea salt to the bowl.
Mix roughly until all the flour is absorbed, adding a few drops of water on the dry spots until it is evenly moistened. It will look a bit shaggy.
Cover, and let it rest an hour.
Right in the bowl, give it a series of pulls and turns (bringing the bottom edges to the top all around the bowl) to develop the structure of the bread.
Repeat hourly (or whenever you happen by your kitchen) about four times or so.
Let rise overnight.
Do a final series of pulls and turns and pop it into a rice flour lined banneton or linen tea towel lined bowl.
Refrigerate at least five hours or overnight before baking.