Bring 8 cups of water to a boil in a large saucepan
over medium heat. Add blackberries, mint, and tea bags. Remove from heat and let stand 1 hour at room temperature. Strain
the mixture through a sieve
, into a pitcher and discard the tea
bags and solids. Add sugar and lemon juice
to the tea, stirring until sugar dissolves. Pour into glasses or cups and garnish
each serving with a mint sprig.