Wash plums and chop them into large pieces to deseed. Place the chopped plums in a pressure cooker, add water and pressure-cook to give 2 whistles. Remove from heat. When pressure drops open the lid, and add the sugar to the hot mixture. Mix well to dissolve sugar. Let it cool.
Place the mixture in a blender and blend till smooth. Strain the mixture.
Add strawberry crush and salt and roughly chopped mint leaves to the plum juice. Check sugar and add some powdered sugar if needed. Chill.
To serve, place a few ice cubes in a glass, pour the cooler. Decorate with mint leaves.