2 tablespoons sugar or honey, plus more, as necessary
1/2 teaspoon fresh lemon juice
6 ice cubes
2 fresh mint leaves
In a food processor, combine the blackberries, yogurt, water, sugar, and lemon juice, and puree. Taste and add more sugar or honey, as necessary. Sieve the mixture to remove the seeds, and reserve the liquid.
To serve, place 3 ice cubes into each of 2 serving glasses, pour over the lassi and garnish with a mint leaf.