Prepare the levain: Mix all of the levain ingredients together in bowl and transfer to a tall-sided glass or other container where you can track the upward growth easily. Make sure that the container is big enough to hold all of the starter at its maximum height (possibly double or triple the starting amount). Track the line where it started with a rubber band or a marker in order to see when it nearly doubles or doubles. The starter is active and ready to use when it looks bubbly and light. At around 23-25C/70-77F it usually takes mine about 4 hours to double, but watch your starter not the clock. **Temp note: if you've got colder temps (18-20C/60F), leave it somewhere warmer in the house (23-26C/70-75F).
Mix: Add the active levain to a large bowl and pour in the water and olive oil. Stir to combine and then pour in the flour and salt. Mix until everything is combined. Cover and let sit for 30 minutes, then with slightly wet hands, perform one very gentle stretch and fold to create a bit of tension in the dough. It’s ok if it tears slightly, it won’t be very elastic.
Bulk Fermentation: Cover and let your dough rest in the bowl until it has doubled in size. You can leave it in the bowl or transfer to a straight-sided container to track its growth. In my kitchen, at (23-25C/70-77F) it takes about 4 hours.
Loaf Tin: Prepare to proof your dough by lining a standard loaf tin with parchment paper (if it’s non-stick, I would just rub a bit of oil with the loaf pan at least). Then with a wet dough scraper or spatula, gently scrape your dough directly into the loaf tin. After, I wet the dough scraper or spatula again and press down until it fills out the tin. Lastly, I drizzle about 1 tbsp more olive oil over the top and spread it around evenly with my hands.
Proof: Cover with plastic wrap or place in a large plastic bag until it reaches the rim of the pan. In my kitchen, at (23-25C/70-77F) it takes about 2 ish hours. If you want, here you can let it proof overnight in the fridge and bake the next morning. Just remember to let it proof outside of the fridge until it reaches the rim of the pan before baking. Bake: Preheat oven to 220C (435F). Remove the plastic covering and place in the oven and cook for 15 min, then lower to 190C (375F) and cook for 25-35 minutes until the internal temp reaches about 95-97C (190-200F).
Cool: Before cutting, make sure to let your bread cool for at least 30 minutes.