Mix the Dough
In a large bowl, mix flour and water until no dry spots remain. Rest for 20–30 minutes. Add sourdough starter and salt, then mix until fully incorporated.

Build Dough Strength
Perform stretch-and-folds or coil folds every 30 minutes for the first 2 hours. The dough should become smooth and elastic.

Bulk Fermentation
Let the dough rise until it has increased about 30–50% in volume and looks airy with bubbles along the sides.

Pre-Shape and Rest
Gently pre-shape the dough into a round. Cover and rest for 20–30 minutes to relax the gluten.

Add the Cinnamon Sugar Swirl
Roll the dough into an even rectangle. Mix sugar, cinnamon, and optional flour, then spread a thin, even layer over the dough, leaving a small border around the edges.

Shape the Loaf
Roll the dough snugly into a log, seal the seam, and pinch the ends closed. Place seam-side down into a proofing basket or loaf pan.

Final Proof
Proof at room temperature until slightly puffy, or refrigerate overnight for a cold proof.

Bake
Bake in a preheated Dutch oven or loaf pan until deep golden brown and fully baked through. Allow to cool completely before slicing.