In England, pickled onions are enjoyed regularly. They are eaten with fish and chips, as part of a Ploughman's Lunch , with meat pies, and so many other savory dishes. There are hundreds of commercial varieties available, both across the pond and here in the States, but nothing beats a jar of homemade pickled onions.
Tiny pickling or button onions are readily available beginning in the autumn and well into the winter.
Small white boiling onions, cippoline onions, shallots and even a few sliced yellow or white onions can be pickled separately or all together. You can also use a variety of vinegars, although it seems malt is the traditional choice for the Brits.