› recipes › quick-pickled-onionsQuick pickled onions recipe | BBC Good Food Boil the kettle. Put the onion slices in a sieve or colander. Pour over the hot water from the kettle and drain well. When cool enough to handle, pack the onion rings into a 500g sterilised jar (see tip below). Pour over the warm vinegar and seal. Cool, then chill and leave to pickle for 2 hrs.