Peel onions, Place in a large dish with salt ; and cover with cold water.
Place a plate on top and press down.
Allow to stand 4 days.
Drain and rinse under cold water.
Combine vinegar, water and sugar.
Cook for 10-12 minutes on HIGH or until sugar has dissolved.
Add onions; cook 2 minutes on HIGH.
Pour into sterilised jars and allow to cool.