Start by making an herbal syrup. Combine the water, sugar, and dried herbs in a small saucepan. Bring to a boil, stirring until the sugar dissolves. Simmer for 1 minute. Then, remove from the heat and steep, covered, for about 30 minutes. Strain and place in the refrigerator to cool completely.

When the syrup has chilled, add it to a blender with the fresh mint and lemon juice. Blend, then add the ice and blend again to make a thick slushy.

Pour into glasses, garnish with mint, if desired, and enjoy immediately!