Make the levain:Take out about 1-2 tablespoon of your starter from the fridge place it in a bowl. Mix with 50 grams of room temperature water and 50 grams of flour (sifted bread flour, whole grain, spelt, or a combo - whatever you prefer as long as the flour to water ratio is 1:1).
Cover the bowl with a plate and leave it on the counter to ferment overnight for approximately 8-12 hours. For more information, see this post on how to make levain.
One Day Before
Once your levain is ready, combine all of it with 350 grams of the water. Add the flour to the water mixture and, and using your hands, mix to combine.
Once the dough is mixed, cover with a tea towel and let it sit at room temperature for 40 minutes to rest.
After the elapsed 40 minute of resting time is up, add the salt and remaining 25 grams water. Mix well until combined then cover with the tea towel and let the mixture sit for 30 minutes.
After 30 minutes, it is time for the first fold.
Do the first fold:To do this get your hands damp and reach under the dough on the opposite side of the bowl from you. Pull the dough up and over towards you. Repeat this so the side closest to you folds over to the side away from you and the side on your left folds towards you right, and your right folds towards your left. Think of it as wrapping a package. Then, scoop your hands under the ball of dough and flip it over completely. This completes one “fold”.
Complete 6 more folds (one fold every 30 minutes) for 3 hours total.
Shaping the dough: Begin by taking the dough out of the bowl and letting it rest on the counter for 20 minutes. Meanwhile, prepare your banneton by dusting it with flour, or layer a clean tea towel in a medium mixing bowl and dust liberally with flour (50-50 wheat flour and rice flour is a great dusting combo).
Shape your dough making sure you get as much surface tension as possible without tearing the outside of the loaf. Once shaped, turn the loaf into the lined and floured bowl or banneton (top-down, seam side up). Gently flour the top (previously the bottom) of the dough before covering with the edges of the tea towel. Set in the fridge overnight.
Baking Day
The next day place your dutch oven in the oven and preheat to 260°C (500°F) or as hot as your oven can go, but no higher than 500°F. After the oven has come to temperature, let the dutch oven continue to preheat for another 30 minutes.
Once the dutch oven has been preheated, take your bread out of the fridge. Gently invert the dough onto a piece of parchment paper that will be large enough to lift your bread into and out of the dutch oven. Gently score the bread with a sharp knife or bread lame.
Using oven mitts, carefully remove the dutch oven from the oven, take off the lid and then carefully lift the dough into the pot using the parchment paper.
Using oven mitts, carefully place the lid back on the dutch oven and put the entire dutch oven back into the heated oven. Reduce the heat to 230°C (450°F) and bake for 25 minutes. Carefully remove the lid (be careful of steam) and bake for another 20 minutes with the lid off.
Remove the pot from the oven and carefully lift out the loaf using the edges of the parchment paper and let cool completely on a wire rack.
Notes
• If heat makes it too difficult to extract the dough and parchment layer safely, just let the loaf cool in the Dutch oven—don't risk burning yourself.