Combine starter and whey or water.
Add 3 cups of the flour and salt, mix until well combined.
Add remaining flour and mix well.
Cover and allow to rest for 30 minutes to an hour.
Every 20 minutes for the next 2 hours perform a set of stretch and folds.
After last stretch and fold, cover and allow to bulk ferment for an additional 2-3 hours.
Turn dough onto work surface.
Prepare the banneton basket or tea toweled line colander by generously flouring the basket or tea towel.
Shape dough and place seam side down.
Cover and allow to rise for an additional 1-2 hours.
Optionally, you can place the dough in the fridge for another 8-12 hours before baking. Put it in the fridge as soon as you get it in the banneton basket and don't allow it to rise first.
Preheat a dutch oven in the oven to 450 degrees F.
Once preheated, remove the dough from the fridge.
Turn the dough out of the basket onto a piece of parchment paper.
Slash top with lame or sharp knife.
Transfer to the dutch oven, put the lid on and bake for 20 minutes.
Remove the lid and continue to bake for 15-20 minutes or until deeply golden brown.