In a large bowl, mix flour and water until no dry spots remain. Cover and let rest for 1 hour (autolyse)
Add the sourdough starter and salt and mix well until incorporated
Cover and bulk ferment at room temperature for 4–6 hours, performing stretch and folds every 30 minutes during the first 2 hours
Once the dough has risen and feels airy, transfer it to a lightly floured surface
Gently stretch the dough out for lamination. Brush an even layer of plum jam over the surface, then fold the dough back together
Shape into a round loaf and place in a floured proofing basket. Cover and refrigerate overnight
Preheat the oven with a Dutch oven inside to 250°C (480°F)
Score the dough, transfer it into the hot Dutch oven, cover, and bake for 20 minutes
Remove the lid and bake for another 20–25 minutes until golden brown and crisp
Cool completely on a wire rack before slicing
