Special equipment: a 60-ounce (7 1/2 cups) pitcher
For the syrup: In a small saucepan, bring the orange juice and sugar to a boil over medium-high heat. Simmer, stirring occasionally, until the sugar has dissolved, about 5 minutes. Remove from the heat and cool for 20 minutes.
For the tea: In a small saucepan, bring the water to a boil. Add the tea bags and remove the pan from the heat. Allow the tea to steep and cool to room temperature, about 20 minutes. Remove the tea bags and discard. Pour the tea and syrup into a pitcher and refrigerate until ready to serve.
To serve: Pour the sparkling water into the pitcher and add the orange slices. Pour the tea into 4 ice-filled glasses. Garnish with fresh mint, or basil, and serve.