An abundance of shallots and some new kilner jars led me to google “pickling onions”.  It sounded easy so I peeled them, salted them overnight, washed them and dried them with a tea towel, packed them into the jars with some peppercorns and just picked bay leaves and then filled one jar with distilled vinegar and the other two with sweetened malt vinegar.  All the recipes say that the hardest part is to wait a month or two before opening.