rinse the raw mangoes in water.steam the raw mangoes in pressure cooker for 3-4 whistles till they become completely soft and pulpy.remove the peel and take out the mango pulp.mix the cardamom powder, salt and jaggery to the mango pulp.mix the ingredients or blend to make it smooth.store in an air tight jar or bottle.while serving, add 1 tbsp of the preserve to one glass of water.stir and add ice cubes.serve cold.