Step 1

In the mixing bowl of a stand mixer, add 1 cup 240 g active sourdough starter, stirred down and 2 cups 454 g warm water. Stir the starter and water together until loosely combined.

Step 2

Attach the dough hook, add in 5 cups 600 g unbleached all purpose flour or bread flour, measured using the scoop + level method (see notes) and 2 teaspoons 12 g coarse kosher salt, and knead the dough for 5- 7 minutes. It will take a while to come together, and it will be a wet dough, but it should slightly pull away from the sides of the bowl and stick to the dough hook. If it's too wet, add a bit more flour.

Step 3

Transfer the dough to a large bowl, with enough room for it to double, and cover with plastic wrap and allow to rest for 30 minutes.

Step 4

Uncover the bowl and perform a series of stretch and folds, recover the dough, and repeat twice more; 30-minute rest then stretch and fold.

Step 5

Recover the bowl and set it aside to rise - 12 - 18 hours.

Step 6

Once the dough has risen, add 3 tablespoons olive oil to a 9 x 13" baking dish (If your dish has a textured bottom, you may want to butter it first).

Step 7

Drizzle some more olive oil on top of the focaccia dough, then using oiled hands or an oiled bowl scraper, carefully deflate and turn the dough out of the bowl into the prepared baking dish.

Step 8

Once the dough is in the baking dish, fold in all 4 sides, long sides first, then short, to create a rough rectangular envelope. Flip the dough over so the seam side is down.

Step 9

Cover the baking dish with plastic wrap and set aside to rise for another 2-4 hours, or until doubled and puffy.

Step 10

Once the dough has doubled, preheat oven to 425f.

Step 11

Oil your fingers with a good glug of oil and spread the oil along the surface of the dough. Then, using your fingers start to poke the surface of the sourdough focaccia. Stretch it to fit the pan if it hasn't spread out completely. Sprinkle generously with flaked salt.

Step 12

Bake the focaccia at 425f for 20-25 minutes or until browned.

Step 13

Cool focaccia on a cooling rack for at least 15-20 minutes before slicing.

Step 14

Garnish with flaked salt + fresh thyme for garnish before serving.