Dry shake = shake without ice. Important to do this whenever you use Puregg white so that it can emulsify with the other ingredients. You will get a much better looking drink with great mouth feel if you do this. Which is the whole purpose of using Puregg whites in the first place!
60ml Blended scotch
30ml lemon juice
20ml sugar syrup
dash of angostura bitters
Dry shake all in a shaker.
Add ice and shake for ten seconds.
Strain into a Double old fashioned glass over fresh ice.