Mix 200 g bread flour with 200 g water plus ¼ teaspoon instant yeast OR 30 g active sourdough culture to create the poolish.
Allow the poolish to sit covered for six hours at room temperature.
In the bowl of a stand mixer, combine the poolish with 200 g bread flour, 100 g semolina, 110 g water, 8 g sea salt, and 5 g instant yeast.
Knead on low speed for 7 minutes, then cover and let rest for 30 minutes.
Turn the dough out onto a lightly floured surface and perform a full stretch and fold.
Let the dough rest for another 30 minutes.
Preheat the oven to 465ºF with a baking stone or a half sheet pan inside.
Divide the dough into four pieces and shape each into a rough rectangle, then let rest for 10 minutes.
Shape each piece into a log by elongating the rectangle and folding over the top third.
Pinch the seam and roll the log to elongate it further.
Arrange the logs on a parchment-lined sheet pan, cover with plastic wrap, and let rest for 20 minutes.
Score the logs down the center and bake in the preheated oven for about 20 minutes.
