Peel the onion. I used a large regular onion.

Slice the onion into very thin pieces using a mandoline slicer.

Place the onion slices on the drying tray and insert the tray into your dehydrator.

Let them dry at 52.5 degrees Celsius (41 degrees Fahrenheit) for 18 hours.

Once dried, let them cool to room temperature.

Now it's time to blend the dried onions. If you have a coffee grinder, it's ideal for this purpose, but you can also use a mini chopper or blender (if you're making a large batch of onion powder).