Making a starter is not absolutely necessary but it will provide a more complex flavor for the dough. Combine flour, water and the yeast in an airtight container and put it into the fridge for at least 4 – 8 hours. It will double in size so choose a big enough box. If starter is NOT used, simply add the amount of flour and water to the dough.
Measure flour, water into a kneading bowl and sprinkle fresh yeast on top. No need to dissolve the yeast. Add starter too or add the amount of flour and water to the dough.
Knead the dough until it comes together. We are after a sticky humid dough.
When handling the dough by hand, flouring will prevent the dough to stick to it, sort of.
Place the dough to a 68°F – 81°F / 20°C – 27°C corner.
Cover it and let it double for 40 – 90 minutes depending on the temperature.
Before start working with the dough again, place a cast iron skillet with a lid into the oven and preheat it to 480°F / 250°C. For some ovens this can take as long as 30 minutes. Cast iron skillet is not obligatory if we have a steam oven or anything that won't melt in the oven, yet won't allow the steam to escape from around the bread. Take the dough out onto a well floured surface. It will stick anyway.
With a floured spatula fold the sides of the dough into the middle.
Repeat several times until a somewhat round, ball shape is formed.
Place the dough into the preheated cast iron skillet as quickly as possible. Mind that it's very hot. If not very familiar how to work with a spatula, prepare the dough by placing it onto a parchment paper and use that to transfer the dough into the skillet easily.
Put the lid on and place it into the middle rack of the preheated 480°F / 250°C oven until crust forms, for about 30 minutes.
Take the lid off and let it bake until golden brown crust forms, for about another 15 minutes.