Recipe courtesy of Tony Abou-Ganim, from his book, " The Modern Mixologist."
In a mixing glass, muddle red raspberries and framboise. Add Bombay Sapphire, egg white, and fresh lemon sour; shake with ice until well blended. Double strain into a Fizz glass and spritz with chilled seltzer water.
To make fresh lemon sour, mix two parts freshly squeezed lemon juice with one part simple syrup.