Fill a mixing glass with ice and stir to chill the glass for 30 seconds, then discard any meltwater.
Add 60ml gin and 15ml dry vermouth to the mixing glass.
Stir continuously for 30–40 seconds until well chilled and properly diluted.
Strain into a chilled cocktail glass.
To garnish with a lemon twist, express the oils over the surface of the drink by holding the peel skin-side down and giving it a firm twist, then place on the rim. Alternatively, garnish with a single cocktail olive.
The ratio of gin to vermouth is a matter of fierce personal preference - Winston Churchill famously implied barely a glance at the vermouth bottle was sufficient. Start at 4:1 and adjust to taste, but never skip the vermouth entirely; without it, you simply have cold gin.
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