Feed your sourdough starter 4-12 hours before starting the dough, giving it time to be active and bubbly.

Combine the warm water, active starter, flour, and salt in a large bowl using a wooden spoon or mixing by hand to form a shaggy dough. Cover with plastic wrap and let the dough rest for 30 minutes for the water to hydrate the flour.

Place the stick of butter into the freezer for about 10 minutes, then grate it with a box grater. Keep the butter in the refrigerator when not in use.

Perform your first round of stretch and folds. Grab the edge of the dough with your hands and stretch it upward. After a good pull, press that edge back down into the center of the dough, turn the bowl a quarter turn, and repeat the process two more times. This is considered one round. Cover the bowl and set aside.

After 30 minutes, uncover your dough for the second round of stretch and folds. Add half of the grated butter at this time, keeping the unused butter in the fridge. Perform the stretch and folds as before, incorporating the grated butter, then cover and set aside.

After 30 minutes, add the rest of the butter to the dough and complete the final round of stretch and folds. Cover and bulk ferment at room temperature for 8 to 12 hours, keeping the dough in a cool location.

Turn your fermented dough out onto a lightly floured work surface and shape into a boule. You can fold it or roll it up, then gently but firmly spin the dough towards you on the counter surface, creating tension on the loaf.

After shaping, place the boule in a floured banneton or a bowl lined with a floured tea towel. Cover and place in the refrigerator to ferment for 12-15 hours.

Set the oven temperature to 425 degrees Fahrenheit. Place your Dutch oven inside to preheat for one hour before baking. Right before baking, remove the dough from the refrigerator and place it on a sheet of parchment paper, seam side down. Dust with flour, if you'd like, and score with a lame.

Carefully transfer the parchment paper with the dough to the hot Dutch oven. Place the lid back on and return to the oven. Bake with the lid on for 30 minutes, then remove the lid and bake for an additional 20-25 minutes until golden brown. Let the loaf cool on a wire rack before slicing.