01 - Combine bread flour and water in a large bowl, mixing until just incorporated. Cover and let rest for 30 minutes to hydrate the flour.
02 - Add sourdough starter and sea salt to the dough. Mix thoroughly until fully integrated and dough begins to develop structure.
03 - Perform stretch and fold technique four times at 15-minute intervals over one hour. Grab one edge of dough, stretch upward, and fold toward center. Rotate bowl and repeat.
04 - After final stretch and fold, gently work cubed cheddar and chopped jalapeños into dough until evenly distributed.
05 - Cover dough and allow to rise at room temperature for 4-6 hours until doubled in size. Dough should show bubbles and feel aerated.
06 - Turn dough onto lightly floured surface. Shape into tight round by folding edges toward center, then flip and smooth. Transfer to floured proofing basket or bowl, seam side up.
07 - Cover and proof for 2-4 hours at room temperature, or refrigerate overnight (8-12 hours) for enhanced sour flavor development.
08 - Position Dutch oven in oven. Preheat to 450°F for at least 30 minutes to ensure thorough heating of cooking vessel.
09 - Transfer dough onto parchment paper. Make shallow slash across top surface with sharp knife or lame. Carefully lower into preheated Dutch oven.
10 - Bake covered with lid for 20 minutes to create steam and develop oven spring.
11 - Remove Dutch oven lid. Continue baking for 20-25 minutes until deep golden brown with crisp crust. Internal temperature should reach 200°F.
12 - Transfer loaf to wire rack. Cool for minimum 1 hour before slicing to allow crumb structure to set and prevent gummy texture.