Put a martini or coupe glass in the freezer for 5 mins to chill. Pour the sake and vermouth into a stirring glass, measuring jug or pint glass and shake over two dashes of lemon bitters. Fill the glass with ice, then stir with a bar or other long spoon for 10-20 seconds (the longer you stir, the softer the taste of alcohol – stir longer for more dilution).

Strain the cocktail into the cold martini or coupe glass, then garnish with a lemon peel twist.