Ingredients:
1k yellow egg plums (stones removed),
1k granulated sugar
Pectin if plums are very ripe (as per instructions on pack)
Method:
Place the plums in a large saucepan (thick bottomed is best), add the sugar and warm on a low heat until sugar has melted, stirring frequently. You will know it has melted if you knock a wooden spoon on the bottom of the pan and don't feel the sugar grains.
Increase the heat to boil the mixture rapidly. Start checking the temperature after 5 or 10 minutes using a jam thermometer. When the jam reaches 104 degrees, take off the heat.
You can also test the jam is ready by placing a small amount on a cold plate, incline the plate and draw a line across the jam : if the line stays clear your jam is ready.
Place the jam in sterilised jars, fill to the top and seal the jars. I find it easier to transfer the jam to a glass jug to fill the jars, it avoids spillages.
Label when cool and place the jars in a cool dry place. It will keep for a couple of years.