Step 02
Cover bowl and let dough sit at room temperature for 12 to 14 hours.
Step 03
Uncover dough and transfer to an oiled work surface. Using oiled hands, press and push the dough into a rectangle, 16×12 inches in size.
Step 04
Fold dough into thirds horizontally, then fold vertically into thirds. Transfer smooth side up into a generously oiled pan.
Step 05
Cover the pan with plastic wrap and let rest until almost doubled in size, about 1 hour.
Step 06
Using oiled hands, fold once more into thirds horizontally, then into thirds vertically to develop gluten structure.
Step 07
Flip dough, smooth side up, on the pan. Cover with plastic wrap and let rest for 1 hour more.
Step 08
Unwrap and stretch and fold dough once more in each direction using oiled hands.
Step 09
Transfer, smooth-side up, into a generously oiled metal baking pan. Lightly drizzle with additional olive oil and stretch to fit the pan. Cover and let rest for 2 hours.
Step 10
Preheat the oven to 425°F (220°C).
Step 11
Unwrap and poke holes in the top of the dough using oiled fingers to create the traditional focaccia texture. Scatter rosemary and flaky sea salt evenly over the surface.
Step 12
Bake in the center of the preheated oven until golden brown, about 30 minutes.
Step 13
Let cool in the pan for 10 minutes, then transfer to a wire rack and let cool to room temperature, about 30 minutes before slicing.