Drying Sourdough Starter

If you want to keep starter unused for a longer period 
of time than a few weeks, or if you want to send some 
through the mail to a friend, you can easily dehydrate 
it into flakes. Using starter that has been fed the day 
before, spread a paper-thin layer onto a sheet of 
plastic wrap and let it sit a day or two until it dries. 
It can then be broken into flakes and stored indefinitely 
in a dry place.

To reconstitute the flakes, put about a tablespoon of 
flakes into a glass or plastic bowl (not metal) that will 
hold about four cups. Mix the flakes with about a tablespoon 
of lukewarm water to form a paste. Gradually mix into the 
paste another cup of lukewarm water, then stir in one and 
a quarter cups of flour. Mix well, although the mixture does 
not have to be free of lumps. You should have approximately 
one cup of a batter the consistency of pancake batter. Cover 
the bowl lightly (not air-tight) and put in a warm spot where 
the temperature is 70 to 80 degrees Fahrenheit (not warmer). 
Allow it to sit overnight.

After standing, there should be bubbles covering the surface 
and the volume should have increased a little. If so, you 
now have a starter. If only a few bubbles have formed, let 
it sit another day. If it appears not to have changed, then 
the reconstitution was not successful.