In a small saucepan, bring 1 cup of water to a gentle simmer. Stir in 1 tablespoon of dried culinary lavender, allowing it to steep for about 10 minutes. Strain and cool the infusion before using.

In the same saucepan, add 1.5 cups of fresh blueberries. Gently mash the berries with a fork while simmering them over low heat for about 5 minutes. Strain the mixture to extract the vibrant juice, discarding the solids.

In a large pitcher, place 0.5 cup of lightly packed fresh basil leaves. Pour in 0.75 cup of fresh lemon juice and muddle gently to release the basil aroma.

Add the strained blueberry juice and the cooled lavender infusion to the pitcher. Sweeten with 0.5 cup of sugar or honey, adjusting to taste. Stir until well combined.

Chill the mocktail in the fridge for about 10 minutes. Serve over ice, topping with sparkling water if desired.