Put the gin alternative, lemon juice, sugar syrup, 3 of the sage leaves and a good handful of ice into a cocktail shaker. Shake hard until the outside of the shaker is ice cold, then double strain into a small jug.

Discard the ice and any remaining sage pieces, then pour the cocktail back into the shaker and add the egg white.

Shake it really hard to froth up the egg white, then pour into a cocktail glass or coupe. Garnish with the remaining sage leaf.