Cut onion into thin half-rings.

In a heavy pan pour the onion with olive oil, sprinkle with salt and, stirring constantly, fry it until transparent. Add the rosemary, Bay leaf, lemon zest, pepper and continue to fry on low heat for 10 minutes.

Bow needs to gain color light caramel, but, if you want darker.

Now add the juice, sugar and vinegar. Stir well, scrape all the caramelized juices. Cover with a lid and leave to languish on low heat for 20 minutes, stirring occasionally.

When the marmalade thickens, and the onion is soft, melting, pull the Bay leaf, rosemary (a few needles will remain in marmalade), lemon zest and pepper. While still hot spread it on a clean, sterilised jars - makes about 300 ml. I keep jam in the fridge, but with the amount of sugar and vinegar, he is probably in the kitchen cupboard perfectly preserved. The jam is much tastier after 1-2 months of storage, but fresh it is quite good.