This is something I haven't done for a few years and we both fancied some so off we went.
We quickly topped and tailed some pickling onions, placed them into a bowl:
Normally I would create my own pickling vinegar but this time opted for bought. Whilst the jars were warming in the oven, the vinegar was heated with 2 - 3 tablespoons of sugar. We like to sweeten the vinegar otherwise it is too acidic for our tastes.
When ready, the onions were stuffed into the jars, a whole dried chilli added, then topped up to just under the brim with the hot vinegar and the lids screwed on tightly. Once cold they were labelled and we'll start on them some time in December: