Line the sheet pan with a silicone baking mat or parchment paper. The silicone mat works best so use it if you have one.

Pour the starter onto the sheet pan and spread it out to a thin, even layer.

Place the pan in a cool, dry place, uncovered. I put mine into the oven with the convection fan on and no heat. Alternately, if you have a food dehydrator you can use that on the lowest temperature.

After 18-24 hours check the starter. It should peel off the mat. If underneath the starter is still moist you can peel it off, flip over the pieces and leave them to continue drying. If using a food dehydrator check after 6-8 hours.

The starter is ready when it is completely dry and crisp. The texture should be like a potato chip which snaps when broken into pieces. You should have half the weight that you started with. If you started with 12 oz of starter you will get 6 oz of dried starter.

Break the starter into chips and store in an airtight container at room temperature.

The dried starter will keep indefinitely. The dried starter chips can be ground into a powder.

Place 1/2 oz (14g) of starter chips or powder in a plastic or glass container. Pour 1 oz (28g) of warm water over the chips and stir to cover the chips with water.

Cover the container and set it aside until all the chips have melted into the water. This usually takes about 3-4 hours. The starter will not look active at this point.

Add another 1/2 oz (14g) of warm water and 1 oz (28g) of unbleached flour to the starter. Stir to combine. Cover and set aside for 4-6 hours. Now you should begin to see activity in the starter.

Add 3 oz (84g) of warm water and 3 oz (84g) of unbleached flour to the starter. Stir to combine. Cover and set aside for 3-4 hours or until the starter has doubled in size and looks quite active.

If after 4-6 hours the starter still seems sluggish, discard all but 3 oz of the starter and do one more feeding.

Use in your recipe as needed.

The amounts listed can be multiplied out to yield more starter.