Remove the outer thick green skin of the watermelon as close to the white rind and possible and discard it. Now remove the out white rind also similarly as close to the red fleshly juice sweet red watermelon as possible. Retain this if you wish, many other items can be prepared with this rind, however it is not used for the preparation of the sorbet.
Chop the red juicy part of the water melon into medium sized chunks. You should have about 6-8 cups of them. Remove the black seeds from the watermelon and discard them. Put the seedless chopped watermelon chunks in a blender and run to a smooth juice. Remove and keep it aside.
In a thick bottomed vessel add 1 heaped cup of sugar, ¼ cup of water, 3 freshly squeezed lime juice and ¼ cup of mint / pudina leaves and bring to a boil. Once it comes to boil, lower the heat and simmer for 5-7 minutes. Remove from heat and cool well.
Once cool strain and add to the watermelon juice and mix well. Pour the mixture in a food grade plastic contained and put it in the freezer to set. Remove after 3-4 hours and beat it with a fork to make it mushly. Put it back in the freezer. Repeat a couple of time if necessary.
Serve the watermelon sorbet in scoops in a glass with spoon.