Super easy pickled onion

[DeGarre]

I might have to improvise with pickling mix, but would this work with malt vinegar?

So I must have made these pickled onions in late August, and forgot about the jar, and found it around Christmas, had a taste and forgot again. I have now been eating them for a week with very nice mature crumbly cheddar. Delicious! Still very crunchy but that's OK. Not too vinegary. Need to prepare a few jars.