In a large mixing bowl, combine 1 cup of the active sourdough starter with 1 ½ cups of water. Stir until well combined. Gradually add in the 4 cups of bread flour and mix until all the flour is hydrated and a shaggy dough forms.
Cover the bowl with plastic wrap or a clean kitchen towel and let it rest for about 30 minutes to allow the flour to fully absorb the water and help develop gluten.
After the resting period, sprinkle 1 ½ teaspoons of salt over the dough. Using your hands, pinch and fold the dough to incorporate the salt until it is evenly distributed.
Cover the bowl again and let the dough rise at room temperature for about 6-8 hours, performing a series of stretch and folds every 30 minutes for the first 2 hours.
Lightly flour your work surface and turn the dough out onto it. Shape it into a round by folding the edges toward the center. Let it rest for 20-30 minutes.
Shape the dough into a tighter round or oval as desired, and place it in a floured banneton or a bowl lined with a kitchen towel. Cover and let proof for an additional 1-2 hours until slightly puffy.
About 30 minutes before baking, preheat your oven to 450°F (232°C) with a baking stone inside, or heat a baking sheet upside down.
Once the oven is hot, gently turn the dough out onto a piece of parchment paper. Use a sharp knife or a razor blade to score the top of the loaf with a few shallow cuts.
Carefully transfer the parchment paper with the dough onto the preheated baking stone or sheet. Bake for 30 minutes, until the crust is golden brown and the internal temperature of the bread reaches around 200°F (93°C).
Remove the bread from the oven and let it cool on a wire rack for at least 1 hour before slicing.