The night before you plan to bake, make your leaven by mixing together 2 tbsp starter with 1 cup flour and 1 cup water. Cover and let sit at room temperature overnight (6-8 hours).
In the morning, weigh out 100 grams of the leaven. Mix with the 350 grams warm water until all leaven has been dissolved. Add 500 grams flour and mix with your hands until no dry spots are there.
Cover and let dough rest for about half an hour.
Mix together the 12 grams salt with 24 grams water. Pour this over the dough and mix well to incorporate. Cover the bowl.
Every 30 minutes (that you're around), "turn" the bread by lifting and stretching the bottoms of each side up and over on top of itself.
Let dough rise (bulk fermentation) for about 5.5-6 hours. Then, place dough on a floured countertop. Gently shape into a ball and cover with plastic wrap. Let rest for about 20 minutes.
Shape dough by flipping it over and folding the top and bottom thirds into the middle, and the sides in as well ---- sort of like a book. Flip the dough back over and shape into a ball. Extra flour is fine here. For this step, I use a blend of rice flour and regular flour.
Place dough ball into a banneton proofing basket (that has been thoroughly floured!!) or a floured dishcloth set inside a bowl. Cover and let rise for about 2 hours.
When you're ready to bake, preheat oven to 500 degrees. Place a dutch oven inside the oven to heat up. Carefully remove the dutch oven once hot and flip your dough inside (this takes a bit of practice but I know you can get it!). Score the top of the dough 3 times with a lame or knife. Immediately place hot cover on the dutch oven and lower oven temperature to 475.
Bake for 24 minutes. After 24 minutes, remove the cover and continue baking for another 24 minutes.
Let bread cool thoroughly propped up before slicing. At least an hour.
You'll never want "normal bread" ever again. Don't give up!!!!