Here are the basics of curing:

• Sun dry for just a short time.
• Cure just the onions you'll store; separate the soft, young and thick-necked bulbs and use them first.
• Cure thoroughly in a warm, well-ventilated area away from direct sun.
• Don't crowd onions during curing; give them room to breathe.
• Onions are ready to store when the skins rattle and the roots are dry and wiry.