Bring 4 cups of water to a rolling boil in a medium saucepan.

Remove from heat and add the black tea bags. Steep for 5-7 minutes, depending on desired strength. Remove and discard the tea bags.

While the tea is still hot, whisk in the granulated sugar until completely dissolved. This creates the sweet tea concentrate.

In a large pitcher, combine the hot tea concentrate with the remaining 4 cups of cold water.

Add the thinly sliced nectarines and the bruised mint leaves to the pitcher. Stir gently to combine the infusions.

Cover the pitcher and refrigerate for at least 2 hours (preferably 4 hours) to allow the nectarine and mint flavors to fully meld with the tea.

Serve chilled over plenty of ice. Garnish each glass with an extra mint sprig or a thin slice of nectarine if desired.