Prepare Dough: In a large mixing bowl, place 250g of active sourdough starter. Zero out the scale and add 725g of warm filtered water. Mix until the starter is dissolved. Add 1000g of flour and 25g of salt. Mix with hand until the dough is the same consistency and there are no pockets of dry flour remaining.

Stretch and Folds: Cover the dough and let it rest for one hour. Perform stretch and folds every 30 minutes for four rounds.

Bulk Fermentation: After the fourth round, cover the dough and let it bulk ferment on the counter for two hours until it increases by 50%-75% in size. (This step may take longer than 2 hours.)

Shaping: Lightly flour the counter. Split the dough in half. Shape the dough into a large rectangle, then fold one side toward the middle, and repeat with the other side. Roll up your dough into a ball shape. Shape it into a round ball by pushing your dough out in a circular motion and pulling in about 3-4 times (tucking in the underside). Let rest for 20 minutes. Perform the final shaping by repeating the steps you did in the first shape. Place your dough upside down (seam side up) into a floured banneton.

Proofing: Cover your dough with a kitchen towel or plastic wrap and cold-proof in the refrigerator for 2 hours or up to 48 hours.

Baking: Preheat the oven to 500°F (260°C) with a Dutch oven inside. Once proofed, flip the dough onto parchment paper. Score the dough. Place the dough with parchment paper into the preheated Dutch oven. Bake covered at 500°F (260°C) for 35 minutes, then uncover and bake for another 10 minutes at 425°F (220°C).

Remove from the oven and cool for at least one hour before slicing.