Place in a bowl the lukewarm water, the sourdough and the salt. Mix until the sourdough and the salt won’t have dissolved in the water.

Add the flour or flour mixture and the seeds (if you so wish) to the bowl and mix with a spoon/spatula until all the ingredients will be mixed together.

Cover the bowl with a towel or any other cover that allows the dough to do some breathing. Let the dough rest for half an hour.

After half an hour, wet your hands with water so that the dough won’t stick to your finger and stretch the dough by bringing one side toward the opposite side. Repeat this for about four times or until the whole dough will have stretched. Now grab the dough with both ends and turn it upside down.

Cover the dough and let it rise at room temperature for about 12 hours.

Pour the risen dough on a well floured surface (a small spatula will be your best friend in this step!) and spread it to form a square/rectangular shape.

Take the left corner, pull it and flip it toward the middle and do the same with the right corner.

Take the upper part and pull it all the way down to the lower part.

With a bench scraper, tuck the dough from all sides to tighten and define a round shape to the loaf.

Flour* a proofing basket or just any kind of bowl lined with a floured dish towel and let the dough proof under a towel for at least 1 hour to up to 3 hours. If you are planning to bake later than that, you can place your dough in a refrigerator for up to 12 hours and remember to take it out 1 hour before baking.

Flour a baking paper and turn your proofing bowl upside down so as to release the dough onto the paper. Slide the loaf into the hot cast iron, cover it with its lid and bake for 30 minutes.

Remove the loaf from the oven and the pan and let it cool.

Store in a breadbox or a metal tin box with a slight loose lid for up to a week.