Blend the tomatoes, olive oil, salt, and the rosemary leaves together until you have a paste (you don't have to blend the rosemary leaves, you can add them whole or chopped to the dough)

In a bowl add the flour, make a well in the middle and add the water, the starter, and the tomato paste and combine until there aren't dry flour particles. Let the dough rest 20 minutes (covered)

Knead the dough until it's elastic and smooth. You can do it manually or with a stand mixer. I'd recommend you let the dough rest 10-20 mins every 5-10 minutes of kneading

When the dough feels smooth and elastic, lightly oil a bowl and place the dough inside to ferment. You can add a coil fold after 30-45mins if you want. At 74-77F (23-25C), my dough was ready after 5h.

Turn the dough onto a floured surface and carefully bring the edges toward the center to shape the dough into a ball, flip it upside down cleaning the flour underneath and with your hands, bring the dough ball toward you to create some tension on the outer layer

Flour a cotton cloth, place it in a proofing basket and put the dough inside. Cover it with the cloth and put the basket in the fridge overnight.

The next day, preheat your oven at 450F (230C) with a pizza stone or a dutch oven if you have , for at least 30-40 minutes

When the oven is ready, take your dough out of the fridge, flip it onto a parchment paper, put it in the dutch oven or the pizza stone and score the loaf (make some cuts on the surface). *SEE NOTES

Put the loaf in the oven and turn the temperature down to 425F / 220 C. Bake the loaf with a lid on (if you're using a dutch oven) or with steam (if you're using a pizza stone or just a baking tray) for 15-20 minutes. Remove the lid and bake the loaf for another 20-30 minutes or until it's golden brown

Take the dough out of the oven and let it cool down in a rack for at least 1h