Bring 3 cups water to a boil in a 2-qt. saucepan. Remove from heat, add tea bags, and stir in fresh mint. Cover and steep 10 minutes.
Discard tea bags and mint. Stir in sugar until dissolved. Pour tea into a 3-qt. container, and stir in 4 cups cold water and lemonade concentrate. Stir in bourbon or spiced dark rum just before serving. Serve over ice. Garnish, if desired.