Prepare the Lavender Simple Syrup: Combine sugar and water in a small saucepan over medium heat. Stir until the sugar is completely dissolved. Remove from heat, stir in the dried lavender buds, cover, and let steep for 15 minutes. Strain the syrup into a clean jar, pressing gently on the buds. Discard the buds and let the syrup cool completely.

Brew the Butterfly Pea Tea: Place the dried butterfly pea flowers in a heatproof container or mug. Pour 1 cup of hot water over the flowers. Allow to steep for 5 minutes until the water is a deep, vibrant blue. Strain the liquid and let it cool to room temperature.

Assemble the Mocktails: In two separate serving glasses (highballs work well), add equal parts of the cooled lavender simple syrup and the cooled butterfly pea tea concentrate.

Add the Acid: Pour the fresh lemon juice into each glass. Observe the color change as the blue tea base turns bright purple/pink due to the acidity.

Finish and Serve: Fill both glasses completely with ice cubes. Top off each glass with about 6 oz of chilled sparkling water or club soda. Stir gently once to incorporate.

Garnish each mocktail with a thin lemon slice and a fresh lavender sprig before serving immediately.