There was recent talk in the press about potential shortages of onions due to the COVID-19 lockdown. If, like me, you panic bought a load which look soon to go off before being used, you can oven dry them to make onion flakes.
Simply heat your oven as low as it can go – usually about 60-70’C.
Slice them as desired and arrange evenly, and well spaced, on a rack (ideally) or oven tray.
Put in oven and leave to dry for anything from 6-10 hours until dry and brittle. You can keep them as onion flakes or once cool, they can then even be ground into onion powder.
You can do the same with garlic.
Link:RECIPE: Marcus Samuelsson's berbere spice mix | Herd Gastronomy %