Vibrant Sourdough You will need to use your own sourdough recipe for reference. I believe the best sourdough would be produced by sprouting rye for 2-3 days and then drying it. Fresh grind the dry rye grains. Sift out 25% of the mixture removing a large portion of the heavy particles. Knead the dough very well and sour for at least 16 hours at 75 degrees F or warmer.