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 sea salt to the dough. Mix until well incorporated and no dry streaks remain.
03 - Stretch and fold the dough 4 times over the course of an hour, performing each fold at 15-minute intervals to develop gluten structure.
04 - After the final stretch and fold, gently knead in the cubed cheddar cheese and chopped jalapeños until evenly distributed throughout the dough.
05 - Cover the dough and let rise at room temperature for 4–6 hours, until approximately doubled in size and bubbly on the surface.
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 refrigerate overnight for enhanced flavor development.
08 - Preheat oven to 450°F with Dutch oven inside for at least 30 minutes to ensure thorough heating.
09 - Transfer dough to parchment paper and score the top with a sharp knife or bread lame. Carefully transfer into the hot Dutch oven and bake covered for 20 minutes.
10 - Remove the lid and continue baking for 20–25 minutes until deep golden brown and crusty sounding when tapped on the bottom.
11 - Cool on a wire rack for at least 1 hour before slicing to ensure proper crumb structure.