Make the lemonade syrup: Peel the lemons into long strips (try not to get too much of the white part, or pith, as it can be bitter) and set aside, then juice the lemons and strain out the seeds.
Place the juice, lemon peels and sugar into a medium saucepan over medium-high heat, stirring to combine. When the mixture starts to boil, reduce the heat to low and allow to simmer for about 15 minutes, until the mixture just barely starts to thicken, then remove from the heat and allow to cool completely.
Make the butterfly pea flower tea: Bring 6 cups of water to a boil and add the tea leaves. Allow to steep for 15 minutes, then strain out the tea leaves and cool completely.
Make the punch: Mix the lemonade syrup and sparkling water in a large punch bowl (start with 2 liters and add more as necessary to taste). Put the butterfly pea flower tea in a pitcher, and place it next to the punch bowl, as well as bowls of lemon wedges and ice cubes and tall glasses.
Guests should put several ice cubes in a glass, then ladle the sparkling lemonade into the glass and squeeze a fresh lemon wedge over the top. Then pour about 1/8 cup of the butterfly pea flower tea over the top to see a magical color transformation!