Why This Works
The highball is the most exposed format in cocktail making — nothing to hide behind, so execution is the recipe. Everything should be as cold as possible: chilled glass, plenty of ice, refrigerated sparkling water. Cold liquid holds carbonation better, and carbonation is the drink's entire texture.
Dilution here is a feature. As the ice slowly melts, it opens up the whiskey's aromatics the way a splash of water opens a neat pour. The drink you finish is subtly different from the drink you started — that slow evolution is the highball's quiet pleasure.
The Alcohol-Free Swap
With only sparkling water alongside it, the alcohol-free whiskey is fully exposed here — this is the drink to make when you want to actually taste your AF spirit.