I finally jumped into the sourdough pool. I am taking the leap with a leap of faith and creating my sourdough starter. This was day one of building it. Day two which you will see tomorrow I named it.  For mine, I am taking an approach that I am using what would be available in an SHTF situation. The chances are we would have access to all-purpose flour. It is basic there is nothing added to it like baking powder and baking soda for self-rising flour. Rye is going through the roof at a price. As for gluten-free, well in SHTF your body will adjust. 

Here is a link to a recipe for a sourdough starter: 

Easy Sourdough Starter Recipe for Making Sourdough Bread Without Yeast

https://www.attainable-sustainable.net/sourdough-starter-recipe/