1. Pour the gin into a large cocktail shaker or mason jar and squeeze in the lemon juice. Add a handful of ice and shake vigorously for 30 secs to chill the gin mixture.
2. Strain the gin mix through the top of your shaker or a sieve into a jug and discard the ice. Pour the gin mix back into the shaker and add the egg white. Shake really well for 30-45 secs.
3. Fill 3 tumblers with ice and add a wedge of clementine. Strain the cocktail into the glasses. Pour in enough soda water to top up the glasses and give each cocktail a brief stir. Serve straight away.