Step 1: Build the Levain Combine the 35g bread flour, 38g whole wheat flour, 70g water, and 7g ripe starter in a small jar or bowl. Stir well, cover loosely, and leave at room temperature for 8 to 12 hours, until bubbly and roughly doubled in size.

Step 2: Mix the Dough Once your levain is ready, combine it with the bread flour, whole wheat flour, rye flour, honey, and most of the water (hold back about 50g). Mix by hand until no dry bits remain and a rough, shaggy dough forms. Cover and let rest for 45 minutes.

Step 3: Add Salt and Remaining Water Dissolve the salt in the reserved 50g of water. Pour it over the dough and squeeze it through with your fingers until fully incorporated. The dough will feel slippery at first, then come back together. Cover and rest for 30 minutes.

Step 4: Stretch and Fold Perform 4 sets of stretch and folds, spacing each set 30 minutes apart. Grab one side of the dough, stretch it upward, and fold it over the center. Rotate the bowl 90 degrees and repeat until you’ve gone all the way around. During the second set, scatter in the diced jalapeños and shredded cheddar, folding them in as you go.

Step 5: Bulk Fermentation After the final fold, cover the dough and let it ferment at room temperature for 4 to 6 hours, until it has grown about 75% to 80% and looks airy with visible bubbles along the sides. Timing will vary depending on your kitchen temperature.

Step 6: Pre-Shape Turn the dough onto a lightly floured surface. Using a bench scraper and your hand, shape it into a loose round by dragging it toward you, building surface tension. Let it rest uncovered for 20 to 30 minutes.

Step 7: Final Shape Flour your banneton well (rice flour works great here). Shape the dough into a round or batard by folding the sides in, rolling it tight, and placing it seam-side up in the proofing basket. Cover with a shower cap or plastic wrap.

Step 8: Cold Proof Refrigerate the shaped dough for 8 to 16 hours (overnight works well). The cold proof deepens flavor and makes scoring much easier.

Step 9: Preheat and Score Place your Dutch oven in the oven and preheat to 500°F (260°C) for at least 45 minutes. When ready, turn the dough out onto parchment paper, score the top with a sharp lame or razor blade at a 30 to 45 degree angle, and immediately lower it into the hot Dutch oven.

Step 10: Bake Bake covered at 500°F for 20 minutes, then remove the lid, drop the temperature to 450°F (230°C), and bake for another 20 to 25 minutes until deeply golden brown. The crust should sound hollow when you tap the bottom. Transfer to a wire rack and wait at least 1 hour before slicing.