Soak half a package of gelatine in a half cup of cold water. Make a syrup of one cup of sugar and one of vinegar, boiled for five minutes; add soaked gelatine to the syrup, add a half teaspoon salt, one cup finely chopped mint leaves and green coloring if preferred (jus a few drops), let stand until cool and strain, or the mint can be left in the jelly if preferred.