Spread them out in a single layer on dehydrator trays and dehydrate for 6-12 hours (at 135°F if you have an adjustable thermostat) or until the cauliflower is about the size of popcorn and is dried through. Open the dehydrator and let the cauliflower cool to room temperature. It will continue to crisp up as it cools. Store in an airtight container for up to a month. If it begins to soften, you can refresh it in the dehydrator for a couple of hours.