This is an easy jam to make purely requiring equal quantities of fruit and white sugar.

First wash the fruits thoroughly and slice them in half in order to de-pit them.  This fruit is unusual in that it has pits with two parts, and they need to prized out.

Then pop them in a blender - skins and all to mush up to an even pulp.

Weigh the fruit at this point so you can then combine with equal amounts of white sugar.  N.B. refined sugar is best as it allows the maximum colour of the fruit to shine through, raw sugar tends to dull it a bit.

Add to a stainless steel saucepan (no aluminimum or iron pots as the acidity of the fruit will impart a metallic taste to the finished jam).

Stir together and cook for around 30 -60 minutes - depending on the batch of fruit.  You can tell when its ready by dropping a dollop of jam onto a cold plate and put in the freezer for a minute or two. If the jam crinkles when you push it across the plate then its ready, if not then cook it longer.

If it looks like its not going to set then add Pectin (quantities will be on the pack).

Pour into scrupulously clean and hot jam jars, add a disc of baking paper on top to minimize contact with air, attach the lid and let cool for a few hours at least.