01 - In a large bowl, mix the bread flour and water until just combined. Cover and rest for 30 minutes (autolyse).
02 - Add the sourdough starter and salt to the dough. Mix until well incorporated.
03 - Stretch and fold the dough 4 times over an hour, performing folds every 15 minutes to develop gluten structure.
04 - After the last fold, gently knead in the cheddar cheese and diced jalapeños until evenly distributed.
05 - Cover the dough and let rise at room temperature for 4–6 hours, until doubled in size.
06 - Turn the dough onto a lightly floured surface. Shape into a tight round loaf and place in a floured proofing basket or bowl.
07 - Let proof, covered, for 2–4 hours at room temperature or overnight in the refrigerator for enhanced flavor development.
08 - Preheat oven to 450°F with Dutch oven inside for at least 30 minutes to ensure proper heat retention.
09 - Transfer dough to parchment paper, score the top with a sharp knife or lame, then transfer into the hot Dutch oven.
10 - Bake covered with lid for 20 minutes to create steam and oven spring.
11 - Uncover and bake for another 20–25 minutes, until deep golden brown and crusty. Internal temperature should reach 200°F.
12 - Cool on a wire rack for at least 1 hour before slicing to allow crumb structure to set.