In a large bowl, add the water and sourdough starter. Whisk them both until the mixture looks milky and fully combined. Add the flour and salt. Mix them all until no dry flour remains and a shaggy dough forms.

Cover the dough and let it rest for about 30 minutes. This step allows the flour to fully hydrate and begins gluten development.

Perform your first set of stretch and folds:

Stretch one edge of the dough upward

Fold it back onto the dough

Turn the bowl and repeat this step 3–4 times

Cover the bowl and let the dough rest for 30 minutes.

In a separate bowl, combine the diced jalapeños and shredded cheddar cheese. Toss them with ½ tablespoon flour. The light coating will absorb excess moisture from the jalapeños and prevent the cheese from clumping.

During your second set of stretch and folds, add half of the jalapeño-cheddar mixture.

Stretch and fold to incorporate.

Then add the remaining half and continue folding until they are distributed to your liking.

At this point, the dough should have some strength, which helps hold the mix-ins without tearing. Cover the dough and let it rest for 30 minutes.

Complete one last set of stretch and folds. At this point, the dough should feel smoother, more elastic, and hold its shape well.

Cover and let it rest for 30 minutes.

Cover and let the dough rise at room temperature (70–75°F) for 4–6 hours until the dough has risen about 50–75% (not doubled). Its edges should look slightly domed and have bubbles on top. The dough should feel airy and jiggle when shaken. (Optional: If you are not in a rush, I recommend refrigerating the dough overnight for a slower fermentation and deeper flavor.)

Lightly flatten the dough, then fold the left side toward the center. Fold the right side over the top and then fold the top down. Roll it up tightly like a burrito. Doing this builds surface tension which will give you a better oven spring.

Place the dough seam-side up into a lightly floured banneton. (Optional: Garnish the top with sliced jalapeños.)

Let the dough rise for either 1-2 hours at room temperature OR in the refrigerator overnight.

Your dough is ready when it looks puffy and springs back slowly when you poke it and there's a slight indentation.

Place your Dutch oven (with lid) into the oven and preheat it to 500°F (260°C) for at least 30 minutes.

Place the dough onto parchment paper seam side down.

Slice the top about ¼ inch deep, then carefully place the dough into the hot Dutch oven.

Bake it covered for about 20 minutes at 500°F.

Remove the lid, and then reduce the heat to 450°F (232°C), and bake it for 20–25 minutes more.

Let your freshly baked bread cool for at least 1 hour before slicing. Cutting too early can result in a gummy texture.