Mix the dough

• Combine the bread flour, lukewarm water, sourdough starter and salt in a mixing bowl.
• Mix until no dry flour remains, then cover and let rest.

Stretch and fold

• Perform four rounds of stretch and folds, spacing them out.
• Cover the bowl between each round.

Set up the float test

• Pour the lukewarm water into a glass.
• Pinch off a chunk of the dough and drop it into the water: if it sinks, it is not ready yet.
• Leave the glass next to the dough, cover both and let bulk fermentation continue.

Wait for the dough to float

• Watch the glass until the piece of dough floats on its own, which signals the end of bulk fermentation.
• Check the dough: it should jiggle and pull away cleanly from the edges of the bowl.

Shape and cold proof

• Shape the dough quickly into a tight round.
• Place it in the banneton and refrigerate overnight.

Bake

• Bake the cold dough in a preheated oven until deeply browned and hollow-sounding.
• Let the loaf cool completely before slicing.