Add the 800 grams of flour to a glass or plastic bowl and then add in the 460 grams water. Then add in your salt.
Last add in the 320 grams of sourdough starter
Mix lightly in the bowl under the dough starts to come together. Once it roughly begins to come together, dump it on your work surface.
Begin kneading the dough to work up the gluten. The dough will be sticky, but DO NOT ADD flour. It makes the dough heavier and will just be absorbed resulting in a heavier bread.
Knead the dough with the palm of your hands. The time you need to kneed the dough will vary from person to person based on your strength. For me it takes 15 -20 minutes. You can tell its done by holding it up. If it stretches without breaking, it's done. If it breaks and tears, keep kneading. It will no longer look or feel rough either and will have more of a smooth consistency when you work it into a ball. You want to have an elastic consistency.
Place the round ball of dough into a bowl and let it proof (sit and rise) for 3 hours. Cover it with a tea towel or cheese cloth.
After three hours the dough will have risen. You want to knock it back somewhat and form it into a round ball. To do this, take each side and fold it back in on itself.
Split the dough into two loaves. You can do this with a bread scraper or I often use a wooden spatula.
Put each ball of bread dough into a proofing basket or a glass bowl. If you're using the glass bowl, place a tea towel or flour sack towel into the bowl first and then flour the bottom and sides well so the dough is less likely to stick. Then flour the top of your dough and fold the towel over it. If you're using a proofing basket, use the liner it comes with and flour the surface. If you don't have a liner flour the surface well.
Let the dough sit for another 3.5 hours. At this point, I put one in the fridge for the next day. The cold air will slow down the rising process. You can actually put both loaves in if you like to make this ahead of time.
About 10 minutes before time is up, preheat your oven to 450 degree and place a pan with water on the bottom rack. This will help to create steam in your oven. This will stop the crust from forming too quickly and allows the dough to open.
Once the time is up, place some parchment paper on the counter and turn the dough upside down onto the paper. Place that piece of parchment paper on a cookie sheet or in your Dutch oven.
You can now score your bread with a bread scorer or a really, really shape knife. You aren't cutting it. You're scoring it.
If you're using a Dutch oven, cover the bread with the lid and put it in the oven directly above the pan with water. If you're using a cookie sheet, make sure your loaf is directly above the pan with water. Don't let the oven hang open. Put your bread in and then quickly close the oven.
Bake for 25 minutes.
When the 25 minutes are up, open the oven and remove the lid from the Dutch oven.
Close the oven again and let the bread bake for another 25 minutes.
Once done, remove the bread from the oven and lift it up on the parchment paper to place it on a cooler surface to cool.
Let bread cool to completely to room temperature before slicing it.