Mash the soaked plum in the same water to get the pulp and take out all the seeds from the pulp.
In a sauce pan, add one more cup of water and let the mixture to boil on low flame.
After that add red chili powder, sugar and vinegar to the sauce and cook on medium heat so that all the sugar dissolve in the sauce and becomes thick like ketchup. it would take 10-15 minutes.
To preserve the plum sauce, let it cool at room temperature,then put the chutney in the jar and wrap a thin plastic or gelatin sheet on the top of the jar so that no air should enter into the jar. In the end, cover the jar tightly with its lid.