In a small pot, crush the mint leaves. Add sugar and water and bring to a boil over medium heat, stirring to dissolve sugar. Allow it to boil for 3 minutes.
Remove from heat and allow to cool to room temperature. Strain out the remaining leaves and then you'll have your simple mint syrup! Set this aside for later.
For the mocktail
In a small bowl, crush the blackberries until you have a nice mush. Mix in the granulated sugar.
Divide the smashed blackberries between 6 glasses and add 2 tablespoons of the simple mint syrup and 1 tablespoon of the lemon juice to each glass. Add your preferred amount of ice to each glass and top off with sparkling water! Garnish with mint ✨