Gargnano lemon and ginger marmalade, Lake Garda

I live in Gargnano on Lake Garda, where lemons thrive in beautiful lemon groves restored by enthusiasts of local traditions. I am lucky to have trees in my garden and use them often. Choose untreated lemons. This marmalade is excellent for breakfast or a snack, or in tarts and biscuits.To remove the bitter aftertaste, I wash the lemons in cold water and brush until shiny.I prick each lemon about ten times all over with a wooden cocktail stick.I soak in cold water for 3 days, changing the water 2 times daily.After 3 days, I remove them from the water.I halve lengthways, slice about 2/3 mm thick, remove seeds and collect escaping juice.I put the lemons in a large, heavy-bottomed saucepan and add the measured water.I bring to the boil, stir and cook partly covered for 30 minutes.Meanwhile, I peel the ginger. Omit if disliked. I love it; the original also praises its properties as well as its distinctive flavour.I grate it.After 30 minutes, I remove the lid and add sugar, ginger and vanilla powder or pod seeds. Do not use artificial vanillin; omit vanilla instead.I simmer gently for about 45/50 minutes, stirring often because it sticks. It becomes jelly-like and looks liquid but sets on cooling. Meanwhile, I sterilise jars and lids by boiling for 20 minutes. I dry them upside down on a tea towel.The marmalade is ready.I fill the jars while it is still boiling hot.I close immediately and invert for at least an hour. I turn upright. The original describes a vacuum forming: when completely cool, the lid should be flat rather than domed. It says a swollen lid means poor closure and advises refrigerating that jar and eating it first.