Steep the Tea: Place the dried butterfly pea flowers in a heatproof measuring cup or bowl. Pour 1.5 cups of boiling water over the flowers. Let steep undisturbed for 5 minutes until the water is a deep, rich blue color. Strain out the flowers and discard them.

Sweeten the Tea: While the tea is still warm, stir in the 2 tablespoons of simple syrup until fully dissolved. Allow the sweetened tea base to cool completely, either at room temperature or by placing the container in an ice bath.

Prepare Glasses: In two tall serving glasses, add a few slices of cucumber to the bottom of each. Fill the glasses about halfway with ice cubes.

Assemble the Base: Pour half of the cooled blue tea mixture into each glass over the ice. Gently top each glass with half of the chilled sparkling water or club soda.

The Color Change: Slowly drizzle 1/2 of the fresh lime or lemon juice over the top of each drink. The acid will react instantly with the blue tea, transforming the color to a vibrant purple or pink. Do not stir vigorously.

Final Garnish: Garnish each Butterfly Pea Flower Tea Mocktail with a sprig of fresh mint and a thin slice of lime or cucumber before serving immediately.