Step 1

Peel and slice the onions. You can use a mandolin to get really even, thin slices. The thinner the slices, the quicker they'll dry. Aim for 1/8 inch thickness (3 mm).

Step 2

Lay the fresh chopped onion over the dehydrator trays in a single layer, taking care not to make them overlap.Dehydrate at 150ºF/66ºC for 6-8 hours (if high humidity, around 80%) or 4-6 hours (if low humidity).They are ready when they snap when trying to bend. If they're at all pliable, they need more time.

Step 3

Spread the onion pieces over parchment-lined baking sheets, making sure the pieces don't touch or overlap and then place them in the oven at its lowest temperature. It's best if the temperature is around 130-150ºF/54-66ºC.If your oven doesn't go as low as that, then choose the lowest temperature and prop open the door with the handle of a wooden spoon or something similar, to allow for better airflow and for the steam to escape as the onion dehydrates.Check on the onion hourly, optionally flipping it over a couple of times, to dry it faster.Remove from the oven when it snaps rather than bends, or at least has a very little bend (as it should continue to crisp while cooling). Once cool, it should snap rather than bend. If not, then it’ll have to go back into the oven again.

Step 4

This option is best for warmer, non-humid climates with lots of sunshine. Colder and more humid areas will affect the drying time.Place the onion slices on a large kitchen towel/cloth or paper-lined baking tray and leave them in a well-ventilated area, near a window (if possible).Flip the onion pieces a few times to speed up the process.This method can take a few days based on the onion's thickness, weather, and humidity.

Step 5

You can use a food processor, blender, coffee/spice grinder, or even mortar & pestle to grind the dehydrated onion into onion powder.

Step 6

Once ground, sift the fine powder through a sieve and re-grind any leftover larger bits. The onion powder is ready.

Step 7

Store the homemade onion powder and flakes in airtight glass jars, and keep them in a cool, dry, and dark location - like a kitchen cupboard.Give the jars a shake the first few days after dehydration, to break up any errant clumps, and optionally place some uncooked rice or beans in the jar to absorb any extra moisture, to avoid clumping.The onion powder and flakes can be stored this way for up to a year, with little decline in flavor. Just make sure to keep the jar 100% moisture-free!