Start off by washing your plums and then cutting them in half and removing the two seeds in the middle. Place them into a non reactive pot. Weigh the plums and add equal parts sugar. 500g = 500g sugar ect.
Add the lemon juice and vanilla pod and heat the mixture over a moderate heat. Stir occasionally until the sugar dissolves. Bring to a light rolling boil and allow to simmer for an hour or until the mixture has slightly thickened.
Test the mixture by putting a small amount on a saucer and place in the freezer for a minute to see if it sets.
Once the mixture is ready, pour out into to jars. Put the lids on immediately and allow to cool before storing.
Recipe by Strayed from the Table at https://www.strayedtable.com/davidson-plum-jam-recipe/