Cut in half and then make slices ~3/8 inches thick.
Arrange the slices on your dehydrator so that there is space around each slice, and the slices are not touching.
Set your dehydrator to the "fruit/vegetables" setting (or 135 degrees F).
Rotate trays every few hours.
Onions are ready when pieces of it break or snap instead of bend. If your pieces are thinner, it will feel papery when ready. (6-12 hours depending on conditions)
If possible, move your dehydrator outside to a safe covered space. The smell of drying onion can be overwhelming to many people.
Dried onions are 3-4 times stronger than fresh.
Dried onions will rehydrate to ~80% of the original size when soaked in water for 30 minutes to 2 hours.
Oven-Drying Instructions: Follow the cutting instructions above and then place onion slices on baking drying racks set in baking sheets.Place in the oven at the lowest temperature possible (usually 140-170 degrees F) and prop open the door with the handle of a wooden spoon. This allows condensation to escape instead of just settle back onto the onions.