Mix the dough

• In a large mixing bowl, whisk together the active sourdough starter, warm water and extra virgin olive oil.
• Stir in the fine sea salt with a spoon.
• Add the bread flour and stir until no dry patches remain.

Rest and stretch and folds

• Scrape down the bowl, cover and rest for 30 minutes.
• Do a first set of stretch and folds.
• Over the next hour, do two more sets of stretch and folds, spaced 30 minutes apart.

Bulk ferment

• Cover the bowl and let the dough rest at room temperature for 4 hours.

Cold proof overnight

• Cover the bowl and place it in the fridge overnight.

Shape into the tray

• Line the baking tray with nonstick parchment paper and drizzle with extra virgin olive oil.
• Tip the dough onto the tray and fold it into thirds.
• Slide it lengthways into the tray, flip it over and cover.

Proof in the tray

• Let the dough proof until spread out, about 2 to 3 hours.
• If it doesn't spread all the way, gently coax the dough towards the edges.

Dimple and top

• Drizzle the dough with olive oil and dimple it with your fingers.
• Scatter over the rosemary and sea salt, making sure the rosemary is oiled so it doesn't burn.

Bake

• Bake on the lowest rack of the oven at 220 °C / 430 °F for 22 to 25 minutes, until the base is crispy.

Finish

• Drizzle with more olive oil at the end.
• Let it cool a little, then cut and enjoy.