Directions:
According to the USDA, to dehydrate onions you need to trim the bulb ends and remove the paper skins. Slice 1/8 to 1/4 inch thick. Onions may be cut into 3/8 to 1/2 inch dice, but will be slightly less pungent when dried. Dry at 160 degrees Fahrenheit for 1 to 2 hours and then 130 degrees until dry. To tell if they are dry they should feel like paper. Dried onions readily reabsorb moisture, causing deterioration during storage, so they need to be packaged in airtight containers and kept in the freezer.