In a large bowl combine the water and sourdough starter together. The mixture should be cloudy when mixed
Add the fresh milled rye flour and salt.
Mix until combined and no dry flour remains. This dough will appear stiff, but the more you work with it, the stickier it gets so just mix and let rise.
The dough will be sticky to the touch but not very slack. This is normal.
Cover and let rise for 8-12 hours or until it has become puffy and feels full of air when poked with a finger.
The dough should have visible bubbles on the surface a be slightly domed in the bowl. This will take varying times depending on the temperature of your kitchen. Longer if the temperature is cooler, less time if your kitchen is warmer. I suggest checking the dough every few hours or mix it up right before bed and it will be ready this next morning.
Generously flour your work surface and turn the dough onto the floured area.
Using a bench scraper or a spatula, lift up on the corner of the dough and fold it back onto the center of the dough.
Turn the dough a quarter turn and continue this all the way around the dough.
Turn the dough over and drag it against the table while cupping the dough in your hands to build surface tension.
Prepare a banneton basket by lining with a linen towel and generously flouring with rice flour or rye flour.
Place the dough in the banneton basket, SEAM SIDE UP, pinch the seams closed, and cover with plastic wrap.
Let rise for 1-2 hours.
Alternatively, you can shape the dough into a loaf shape and do the second rise in a greased or parchment lined loaf pan.