In a large bowl, mix the bread flour and water until just combined, then cover and let it rest for 30 minutes (autolyse).
Add the sourdough starter and salt to the dough and mix by hand until fully incorporated into a shaggy dough.
Cover the bowl and let the dough rest at room temperature for 4–5 hours, performing a set of stretch and folds every 30 minutes.
Once the dough has increased by about 50% and feels airy, turn it out onto a lightly floured surface and gently shape it into a round or oval.
Place the shaped dough seam-side up into a floured banneton or bowl lined with a floured towel.
Cover and refrigerate overnight (8–12 hours) for cold proofing.
Preheat the oven to 475°F (245°C). Carefully invert the dough onto parchment paper, score the top with a sharp blade or razor, and place it on a hot baking stone or tray.
Bake for 20 minutes with steam (add a tray of water or spray inside the oven), then remove steam and bake for another 15–25 minutes until deep golden brown.
Let the bread cool completely on a wire rack before slicing.