Prepare the Blackberry Syrup: In a small saucepan, combine the 1 cup blackberries, 1/2 cup sugar, and 1/2 cup water. Bring to a simmer over medium heat, stirring until the sugar dissolves completely.

Cook the syrup for about 10 minutes, pressing the berries gently with the back of a spoon to release the juices. Remove from heat and let it steep for 5 minutes.

Strain the syrup through a fine-mesh sieve into a bowl, pressing gently on the solids to extract all liquid. Discard the solids. Set the syrup aside to cool slightly.

Brew the Tea: Bring 6 cups of water to a boil in a medium pot. Remove from heat and immediately add the tea bags. Steep for 5-7 minutes, depending on desired strength. Remove the tea bags and compost.

Combine and Chill: Pour the steeped tea into a large pitcher. Stir in the cooled blackberry syrup until fully incorporated. Taste and adjust sweetness if necessary by adding a splash more water or sugar slurry.

Chill thoroughly in the refrigerator for at least 1 hour. Serve over plenty of ice, garnished with fresh lemon slices and a few extra fresh blackberries.