Prepare plums - Wash and dry the fresh plums. Slice plums in half and remove the pit. Dice plums into 2” chunks.
Cook the plums - Add the chunks of plum and all other ingredients into a large saucepan. Bring the ingredients to a boil. Reduce the heat to a simmer, cover with a lid and cook for 25 minutes.
Remove the pan from the heat. Allow the mixture to cool for about 15 minutes. (Set saucepan aside for use in future steps)
Puree the mixture in a blender or food processor until smooth.
Pour the pureed mixture back into the saucepan. Bring the sauce to a boil. Stir the sauce and cover. Reduce the heat to a simmer.
Simmer the sauce for an additional 20 minutes. Stir once after 10 minutes of cooking.