Prepare the fruit (core apples, remove unwanted seeds from other fruits, etc.) and cut up the fruit into manageable pieces.
Process the fruit in a blender, food processor or food mill until the mixture is relatively smooth.
Mix in the spices, sweetener, and whey or water kefir.
Transfer to a quart jar, leaving at least an inch of headspace.
Cover the jar with a tight lid, airlock lid, or coffee filter secured with a rubber band.
Culture at room temperature (60-70°F is preferred) until desired flavor and texture are achieved, about 1-3 days. If using a tight lid, burp daily to release excess pressure.
How To Dry the Fruit Leather:
Spread the cultured fruit mixture on sheets of unbleached parchment paper or a silicon sheet that fits inside your food dehydrator, or on a baking sheet if using your oven. Tip: If the mixture is very watery, try straining the mixture through a tea towel or tight-weave cheesecloth to thicken it up a bit. The strained juice is delicious to drink and contains beneficial bacteria from the culturing process.
Allow the fruit leather to dry overnight or for 8 to 24 hours. The exact length of time will depend on the temperature used and the thickness of the mixture. We recommend setting your oven or food dehydrator to 110°F or less to preserve the beneficial bacteria.
The fruit leather is done when it is smooth and no longer sticky.
Store the finished fruit leather in an airtight container.