I'm a bit unsure about Onion marmalade, not the taste or concept, just the naming of it. In my mind a marmalade is a fruit preserve, made from citrus fruit. However, fashion has invented a version using onions, which I guess tends to be sweeter and more jam like than an onion chutney, so I was tempted into trying it out using some of the onions still laid out in the greenhouse.
I tried to keep the recipe simple and not go down the 'slow caramalised heritage variety red and white onion marmalade with single estate vintage balsamic vinegar' route. I did succumb to the addition of caraway seeds, as I'd never seen these used in a preserve before.