Make the dough: In a large bowl, whisk together the flour, yeast, and salt.
Add warm water and olive oil (if using). Stir with a spatula until no dry spots remain. The dough will be very wet and sticky—that’s correct.
Rest (autolyse): Cover the bowl and let the dough rest for 20–30 minutes.
This helps the flour hydrate and makes gluten development easier.
First stretch-and-fold: With wet hands, grab one edge of the dough, stretch it up, and fold it over the center. Rotate the bowl and repeat 4 times to form a rough ball. Cover and rest 30 minutes.
Repeat folds: Do 2 more rounds of stretch-and-folds, 30 minutes apart.
Each time, the dough should feel smoother and hold its shape a bit more. Keep your hands damp to prevent sticking.
Bulk rise: Cover the bowl and let the dough rise in a warm spot for 1–2 hours, or until it’s puffed and roughly doubled. It should wobble like a soft pillow when you jiggle the bowl.
Prepare the bake setup: Place a baking stone or an inverted sheet pan in the oven and preheat to 475°F (245°C) for at least 30 minutes.
Place an empty metal pan on the lower rack for steam.
Shape gently: Generously dust your counter with flour or semolina. Carefully scrape the dough onto the floured surface, trying not to deflate it. Dust the top with more flour.
Using a bench scraper, gently coax it into a rectangle about 1 inch thick. Cut into two equal pieces.
Final shaping: With floured hands, lift each piece and lightly stretch into a longer slipper shape. Don’t press down; keep as much air inside as possible.
Place onto a parchment sheet dusted with flour or semolina, leaving space between loaves.
Final proof: Cover loosely with a towel and let rest 30–45 minutes, until slightly puffy. Meanwhile, bring 1 cup of hot water to a boil for steam.
Steam and bake: Slide the parchment with the loaves onto the hot stone or sheet pan. Carefully pour the boiling water into the empty pan below and close the oven quickly to trap steam.
Bake 12 minutes, then remove the steam pan, rotate the loaves, and bake another 10–15 minutes, until deep golden brown.
Cool completely: Transfer to a rack and let cool at least 45 minutes. Cutting too early can squash the crumb and make it gummy.