Add 2 or 3 ice cubes to a glass and pour in the club soda and orange syrup.
Use a small ice cream scoop and add one (or two) scoops of sherbet and vanilla ice cream. Top with a sprig of mint.
Notes
Use a tall glass: Leave plenty of room at the top for the sherbet and ice cream. The soda may foam as the scoops settle into the glass.Adjust the orange syrup: Use a little more or less syrup to control the strength and sweetness of the orange flavor.Try the orange-soda shortcut: Orange soda can replace both the club soda and orange syrup, although the finished drink will be sweeter.Serve it right away: The soda is best while it is still fizzy and the sherbet and ice cream are just beginning to soften.Stir gently: Use a straw or long spoon to slowly blend the melting sherbet and ice cream into the soda without losing too much carbonation.