Bartender Laura Kelton is a fan of Prince, but the Purple Rain in the reference comes from the drizzle of creme de cassis that cascades through this take on the Bramble cocktail.
The Bramble, of course, is the classic cocktail of a gin sour sweetened with a blackberry liqueur. Kelton serves her version in a highball, adds a bitter element in the Suze, and substitutes blackcurrant liqueur in the form of creme de cassis.
1.5 oz. gin
0.5 oz. Suze
0.5 oz. simple syrup
1 oz. lemon juice
Splash of soda water
Drizzle of creme de cassis
Combine over rocks. Top with soda water. Mix together. Finish with a drizzle of creme de cassis.