Feed your sourdough starter and let it become active and bubbly
Line a baking sheet, silicone mat, or parchment paper with a thin, clean layer of starter
Spread the starter as thinly as possible
Let it dry at room temperature until completely hard and brittle
Break the dried starter into flakes or pieces
Place the pieces in an airtight container or vacuum-seal bag
Store in a cool, dark, dry place
Label with the date
To use later, rehydrate with equal parts dried starter and warm water by weight
Stir and let it sit until softened
Add flour and continue feeding until active again