4lbs of strawberries, better slightly under than over ripe
juice of 2 lemons
6 jam jars
6 disc's of greaseproof paper
I like to wipe the strawberries clean (mainly because Delia says so, water can dilute pectin apparently) and cut to desired size. If they are small enough I like to leave them whole however these were hand sized brutes so required some chopping. Some people like to mash them...Your call. Put a small plate in the freezer which you will need later. Put the clean jam jars in a low oven to warm.
Put strawberries and sugar in to a large heavy bottomed pan, all the better if you have a proper preserving one (I don't), and heat gently. Once the sugar has dissolved add the lemon juice and wack up the heat to bring the mixture to the boil.
Do not be concerned about the scum. Some recipes say to skim it off at the end, I don't bother. A lot of it dissipates by the time you get to putting it in the jars. Now the next stage requires patience and stirring. You need to stay by the pan (once you've had jam boil over you won't leave it again!) and keep stirring to prevent it catching on the bottom and burning. It takes about 25-35mins for it to reach setting point and to get to a temperature between 209-220F. Mine took a little longer than 35 minutes and was up to 220F. I would like to say I can look at it and tell when its ready, or judge by the consistency but I can't. This is where the plate in the freezer comes in. Put a blob on the plate and if it wrinkles up when you push it (after its cooled) its ready. Strawberry jam can be a soft set, so in this instance the 'wrinkles' were very slight on the surface of the jam.
Remove the pan from the heat and stir in a knob of butter, this helps get rid of the scum. Leave the jam to cool for about 15 minutes before decanting into the clean, warmed jars. I use a jam funnel and ladle for this process.