According to Stephen Fry, on QI, who could not tell a lie:

The teeth etching thing is less of a worry than, say crisps (chips), because the liquid is gone in an instant, whereas the potato starch is likely to stick to your teeth. Given the QI contorted postulations designed to obfuscate, is that the case?

So maybe crisps first and phosphoric acid to remove the lingering starch after. Though not for me.

But I bet chocolate would stick around longer.