Chop the ends off the lemons and then slice them very thinly. Pack the lemons and the chillies into a sterilised glass jar and layer with salt, adding the bay leaf about half way down. Top with fresh rosemary and a final layer of salt and tightly pack. Top up the jar with warm water, making sure that the lemons are covered. Seal with a lid, give it a good shake and store in a dark cupboard for two weeks.
It's delicious chopped into sauces, you can use it to make gremolata with a difference, and it's great in a dressing or stirred into savoury rice.