Fill a mixing glass two-thirds full with ice cubes.
Add 60ml Scotch whisky and 20ml dry vermouth.
Stir continuously for 30 seconds until well chilled and properly diluted.
Strain into a chilled cocktail glass.
Express a lemon peel over the surface to release the oils, then drape over the rim or discard as preferred.
The ratio is key here - too much dry vermouth and the whisky gets lost; too little and the drink becomes flat and one-dimensional. A 3:1 ratio of Scotch to dry vermouth is the sweet spot, and a blended Scotch works beautifully, though a lightly peated expression adds compelling depth.
My Bar Shelf reads your shelf and shows you every cocktail you can make from what you already own, including Dry Rob Roy.