Mix the dough: In a large bowl, combine the ripe starter, water, and flours. Stir until a sticky, rough dough forms. Let rest for 20 minutes (autolyse).
Add salt and knead: Sprinkle in the salt (and yeast, if using). Knead by hand for 5–7 minutes or use a stand mixer for 3–5 minutes until smooth.
Bulk fermentation: Place dough in a greased bowl, cover, and let rise for 1.5–6 hours at 70°F, folding every hour.
Shape the dough: On a floured surface, preshape into a ball, rest for 15 minutes, then shape into a boule or log.
Final proof: Place in a banneton or greased pan, cover, and let rise for 2–3 hours (or refrigerate for 12–48 hours).
Bake: Preheat oven to 450°F with a Dutch oven inside. Score the loaf, bake covered for 45 minutes, then uncovered for 10–15 minutes until golden (210°F internal).
Cool: Cool completely on a rack before slicing.
