Wash the jambu thoroughly and soak them in clean water for 10-15 minutes.
Put the cleaned jambu and water in a pan ( the water should be at least one inch above the submerged fruit).
Place the pan on fire and cook the jambu on a medium heat until its pulp separates from the seed/stone. This should take around 10-12 minutes.
Add sugar as per your taste. The amount of sugar required will also depend to sweetness of the Jambu.
Let the mixture simmer for a couple of more minutes until the sugar dissolves.
Remove from fire.
Allow the mixture to cool thoroughly.
Massage the mixture with hands to completely separate the flesh from the seeds.
Strain the mixture and add cold water enough to make 5 glasses of sherbet.
To the prepared sherbet add roasted cumin powder, rock salt and salt to taste. Stir well.
Allow it to chill in the refrigerator.
Serve chilled.
