In a large mixing bowl, combine 500g bread flour and 350g water. Mix in a circular motion until no dry flour remains. Cover and let it rest (autolyse) for 20 minutes.

Grate the cheddar cheese and place it to the side.

Remove pickled jalapenos from the brine and place into a small bowl and set aside. If using fresh jalapeños, then slice the jalapenos and place them to the side.

Add 100g of the active sourdough starter and 10g salt to the autolysed dough. Mix thoroughly until well combined. Let the dough rest for 30 minutes.

After the initial rest, fold in the chopped jalapeños and shredded cheddar cheese. Make sure they are evenly distributed throughout the dough. Cover with a damp cloth or plastic wrap and let the dough rest for 30 minutes. 

After the resting period, use a dough scraper, bench scraper, or wet hands to gather the dough from one edge of the bowl and perform the first set of stretches and fold by gently stretch the dough out, and fold it back onto itself. Rotate the bowl a quarter turn and repeat the action. The dough will take on a somewhat square shape. Cover the bowl with a damp tea towel and let the dough rest for another 30 minutes.

After the 30-minute rest, conduct another round of stretch and folds. Stretch the dough from opposite ends and fold them over each other. Rotate the bowl and repeat. Cover the bowl and let the dough rest for another 30 minutes. Repeat this sequence two more times, for a total of three sets of stretches and folds.

Place the dough in a bowl, cover it with a damp towel or plastic wrap, and let it rise at room temperature for about a 4-6 hour period, or until it has roughly doubled in size. The exact rising time will depend on the temperature of your kitchen and the activity of your sourdough starter.

Shape the dough into a smooth ball or oval, similar to the shape of your banneton or proofing basket. Place dough into a floured banneton and cover with plastic wrap or a damp tea towel. You can place the dough into the fridge for 3-4 hours before baking it or you can refrigerate overnight for the final rise.

Remove the banneton from the fridge and place the sourdough dough on a piece of parchment paper. Score the top of the dough. Preferably down the middle of the dough so it encourages a good oven spring.Transfer the sourdough, with the parchment paper under it, to the Dutch oven.Place the lid on the Dutch oven and put it into the oven.Turn the oven on to 425°F and bake for 55 minutes.After 55 minutes, remove the lid. If the loaf color is to your liking, remove the sourdough from the Dutch oven and place it on a cooling rack. If not, bake for another 5 minutes with the lid off until the desired color of golden brown is achieved.

Allow the loaf of bread to cool for at least 1 hour before cutting into it to avoid a mushy crumb.

Enjoy your homemade jalapeno cheddar loaf!