1-First Step: In a large bowl, combine 50 to 100 grams active sourdough starter, 10 grams kosher salt, and 430 to 440 grams room temperature water. Stir to mix; the liquid does not need to be uniform. This initial mix hydrates the starter and salt.

2-Second Step: Add 512 grams bread flour and mix until the dough forms a sticky ball. No kneading is required; just incorporate until no dry streaks remain.

3-Third Step: Optionally perform one fold about 30 minutes after mixing. To do this, pull the dough from one side and fold it into the center several times while turning the bowl. This single fold can help gluten development and improve structure.

4-Fourth Step: Drizzle the dough with a splash of olive oil and rub it to coat the surface. Cover the bowl with a tea towel or bowl cover and let the dough rise at room temperature (about 70ºF/21ºC) for 4 to 18 hours, until nearly doubled. Warmer kitchens shorten the rise; cooler kitchens lengthen it.

5-Fifth Step: Place 2 tablespoons olive oil in a 9×13-inch pan. Drizzle an additional tablespoon of olive oil on top of the dough. Gently deflate the dough, transfer it to the oil-coated pan, and shape it roughly into a rectangle with the seam side down.

6-Sixth Step: Rub more oil on top of the dough, leave it uncovered (or cover loosely if the air is dry) and let it rise for a second time at room temperature for 4 to 6 hours until puffy and nearly doubled.

7-Seventh Step: Preheat the oven to 425ºF while the dough completes its second rise. Oil your hands lightly and dimple the dough with all fingers, stretching it gently to fill the pan.

8-Eighth Step: Sprinkle generously with flaky sea salt and any additional toppings like rosemary, thyme, or halved cherry tomatoes. Bake for 25 minutes or until golden brown on top.

9-Ninth Step: Transfer the baked focaccia to a cooling rack and cool at least 20 minutes before slicing. This resting time helps the crumb set and prevents a soggy bottom.