Whisk water and starter together vigorously in a see-through mixing bowl with your danish whisk until it bubbles up.
Add your flour and mix until it all comes together. (this may take a few minutes as the dough is very thick.)
Let sit for 30 mins in a warm place. *I like to cover mine with a damp tea towel.
Then add salt for your first stretch and fold.
30 mins later, stretch and fold for the second time.
30 mins later, stretch and fold for the third time.
30 mins later, stretch and fold for the final time.
Cover with a damp tea towel and let rise 50-75% *I check the proof after 3.5 hours as I’ve learned that it is perfect for my home. If you’re a beginner, check after the first 3 hours and then every 30 mins until it reaches 50-75% rise.
Once your dough has grown to size, take it out of the bowl and shape it on the counter.
Let it rest for about 20 more minutes on the counter then shape again. Flour your banneton generously and flip your bread dough into it so the bottom is now on top.
Cover with a damp tea towel and put it in the fridge overnight (for the best taste!) or bake later the same day after a few hours of chilling.