Whisk the sugar and pectin together in a medium bowl. Set aside.

Put mint leaves and stems in a large, heavy-bottomed pot and crush them gently with a wooden spoon. Add vinegar, water, and  bring to a boil over medium-high heat. Add the sugar-pectin mixture and return to a boil. Boil hard for one minute.

Pour jelly through a cheesecloth-lined sieve into a large bowl. Discard mint leaves. Pour jelly back into pot and return to a boil. Remove pot from heat. If stroing ,ladle jelly into hot, sterilized jars and process in a hot water bath for 20 minutes.

Note: if pectin does not work adequately , heat up again and add a pack of gelating