Place chopped mint leaves in a crock or deep bowl; add boiling water. Place a flat dish over the leaves and weight it down. Allow to stand overnight. Bring sugar and 3 cups water to a boil and cook 10 to 15 minutes. Meanwhile, squeeze the juice from the mint leaves; add mint juice to the syrup, bring to a boil, cook 5 minutes and remove from heat. Discard leaves. Add green food color to make the syrup a bright green. Add the mint oil and stir. Pour into sterile bottles. Refrigerate. Syrup is ready to use. Dilute with cold water or sparkling water. SOURCE: Sabbath chapter in _From My Grandmothers Kitchen: a Sephardic Cookbook_ by Viviane Bichech Miner