1Peel the onions and place in a large bowl. Cover with water and 1 TBSp salt per bowl. Soak overnight in the fridge.
2Sterilise your chosen jars. Add the onions to the jars. Then add the pickling spice and top up with the mixed vinegars.
3Cut a small circle from the wax paper (enough to cover the top of the jar) and place over the top of the jar. Screw the lid on tightly.
4Store the jars filled with the pickled onions in the fridge for at least a week before eating.