You might look into walnut oil as a finish, if you're concerned with
food safety, but most all finishes, once fully cured, are safe unless
you eat them. In the case of shellac, it's used to coat tablets, like
asprin etc., so I guess it's safe. Friction polishes are fairly quick
and easy, and durable enough if you don't immerse or put in the
dishwasher.
I like the platter, nice tight joints and nice shape!
Have you considered a vacuum chuck for reversing your work? Easy to set
up if you have a vacuum source.