In a Collins glass, add 1 to 2 ice cubes and stir rapidly for 20 seconds to chill the glass. Hold back the ice with a barspoon while draining off the water.
Add the whisky and stir clockwise exactly 13½ turns. Set the spoon on the lip of the glass, with the end resting on the counter.
Add the mineral water, then use the spoon to stir exactly 3½ times to blend.