1) Chill a martini glass with ice and water. Separate an egg white from the yolk. Add white to cocktail shaker with gin, pomegranate juice, sugar, and bitters (opt.). Add lid to shaker and shake vigorously for 30 seconds. Mixture should be frothing and foamy.
2) Add ice to cocktail shaker and shake a second time, vigorously, for 30 more seconds.
3) Strain cocktail into chilled glass. Garnish with lemon rind slice. Serve immediately while very cold.