I am a jam making novice. In fact, I have never made jam before. I don't have a jam pan, thermometer, maslin pan or funnels and I still managed it.
I followed a very straight forward recipe for Savoury Plum Jam in Sarah Raven's Garden Cookbook (you'll find it under July-August, I'm afraid up north our plums are a bit behind).
For 3-4 jars you need:
1kg plums (stoned)
750g granulated sugar (I used a bit of caster too)
300ml warm water
25g finely chopped stem ginger (you could get away with more ginger if you like the heat)
Here's what to do:
Halve or quarter the plums and remove stones.
Put everything in a thick bottomed pan and allow to stand for an hour.
Warm the mixture slowly to dissolve the sugar, stirring for the first ten minutes.
Turn up the heat and bring to a rolling boil. The recipe says cook for about 15 minutes but I needed 30 minutes to reach setting point.*
Jar, cover, seal and store for up to a year (in the fridge once opened).
Sarah does call this a savoury plum jam but I'd have to say it tastes pretty sweet to me. I'm not skilled enough to play with the sugar quantities just yet but I'm happy with a sweet jam for all my toast and jam sandwich needs.
To test the setting point, according to Sophie Grigson remove the pan from the heat. Take your saucer from the freezer and place a drop of jam onto the cold plate. After a few seconds push the jam with your finger.
If the jam surface wrinkles then it has reached setting point and is ready. If it slides about as a liquid, then it hasn't reached setting point and should be returned to the heat and boiled for a few more minutes before testing again.