In a cocktail shaker with a few ice cubes, add in the vodka, lemon juice, egg white (optional) and Angostura bitters (optional).
Shake well for 1 minute or so until chilled.
Strain the mix through the cocktail strainer and the fine mesh strainer into a glass filled with ice. The foam will float up top, but you can use a bar spoon to collect any foam that does not pour out.
Garnish with the lemon wedge and cherry on a cocktail pick.
Notes
For a vegan recipe, substitute the eggs with aquafaba. But make the froth separately. Two tablespoons of aquafaba is equal to one egg white.