In a medium saucepan, set over medium heat, add the chopped rhubarb, water, sugar, lime juice and pinch of salt. Cover the pan and cook until the rhubarb softens and becomes all juicy and stuff, about 5 to 7 minutes. Run the syrup through a strainer, discarding any rhubarb bits, and allow to cool completely.

To a cocktail shaker, pour in the gin, egg whites, heavy cream, lime juice, rhubarb syrup and generous handful of ice. Give it a shake, for about a minute, I’m talking REALLY shake it—it should be frothy and cold. Divide the egg white fizz between the two glasses. Top with a slash of soda water.