In a large pitcher, blend the 2 cups of fresh lemon juice with 1 ½ cups granulated sugar. Stir constantly until the sugar dissolves completely.
Slowly add in the chilled, unsweetened black iced tea and stir gently to combine all the flavors.
Fill tall glasses with ice and pour the refreshing mixture over it. Optionally, garnish with a sprig of fresh mint and a lemon slice on the rim.
For a spirited twist, add 1.5 oz of your favorite liquor (vodka, bourbon, or sweet tea vodka) to your glass before topping with the tea and lemonade.