1.5cupswatermake it 2 cups if you like the jam to be a bit runny and not too thick
Wash the plums, remove the seeds and then chop them. Add to the pot.
Add water to chopped plums, turn heat on high. Add sugar and mix slowly until all sugar has dissolved. Once water has started to boil, stop stirring. Add lemon juice and lemon zest.
Lower temperature to medium. A foam might form, but you don't have to remove it. It will get absorbed again into the jam mixture. After about 20 minutes lower temperature to low. Cover and let it simmer for another 25 minutes. By then jam should be thick, still a bit runny and as it chills it should really set.
Let it cool in the pot. Once cool enough to handle, use a ladle to pour over a glass jar (sterilize the glass jar before hand in a pot of boiling water). Cover the jar and store in the refrigerator. Enjoy it over toast or any dessert of choice!
If using black plums (like in my video), than I suggest adding the sugar over the chopped plums and let the plums absorb the sugar for about 15 minutes or so, then boil.