Place the lemons in a thick based saucepan, along with the water.
Put the lid on and simmer gently until the lemon peels are cooked through. This will take about 30 minutes.
Remove the lid and boil fast until there is just a very small amount of water left.
Leave until cool and remove the pips.
If you would like some bits in your jam, remove one half now. Cut that half into small lumps or shreds
Puree the remaining lemon halves into a smooth pulp using a food processor, stick blender or liquidiser, adding the shreds, if any, back in now.
Now weigh the puree and add the same amount by weight of sugar.
Put back on the heat and blip gently for about 10 minutes. Be careful, it's a thick mixture and may splash.
You can test the set by putting a teaspoon of jam on a cold saucer and putting it in the fridge for a couple of minutes. If it’s ready, it will have formed a skin in that time and when you push it gently with a finger you’ll see that skin.
If you have a thermometer able to measure high enough, it should set when it reaches 104c/220f. Just keep simmering until it’s ready. Although being all lemons, there is masses of pectin and it will set solid.
While the jam is simmering, sort your jam jars out. If you haven’t already, wash them, and pop them in a low oven to sterilise them. Some people use jars fresh from the dishwasher. Whatever you do, they need to be very clean, and dry.Any water in the jars allows a sugar syrup to develop, and over time, that may well grow mould, spoiling your lovely jam. And they need to be scrupulously clean so your jam will keep well, there must be no germs, bacteria or mould spores at all in the jars.And don’t forget the lids. If you are not using lids, cover the jars with cellophane circles and elastic bands. Or use circles cut from cereal box inners and perhaps a pretty ribbon. A little gingham fabric looks fabulous. Anything that will keep the jam clean and dry will do the job.
Once the jam is ready to set, there may be scum on the top. Either skim it off, or stir in a generous knob of butter, this gets rid of any scum floating on the surface. Stir well. Leave to cool for about 10 minutes, stirring now and again
Put your jars on a heatproof surface and carefully ladle in the jam. Be careful, splashes will burn you badly at this temperature. A jam funnel is helpful for this
I usually put a very clean tea towel over the filled jars until they are just warm and only then put the lid on. The tea towel is to keep any mould spores in the air, off the surface of the jam.Others have recommended putting the lids on straight away and turning the jars upside down
I used 3.5 lemons and it made almost 2 jam jars full.
Nutrition per tblspThis is just as nice using zested and juiced oranges.