Originally Posted by
GNRMatt
And what exactly is a "katotaan"?
And about your initial question: It appears that some sauces are indeed in a disposable ramekin that the FA pours on the plate before serving, but this is not guaranteed. They're more accommodating towards AY Plats than others, but if you get a good crew, you could try to explain in a way that's a bit apologetic that you'd love dish X, but can't eat the sauce because of your allergy and ask nicely if the sauce comes in a separate ramekin that could be left out. Chances are that if you're nice about it, they'll be nice, too.
I wouldn't take the chance of preordering, though, in case they can't accommodate your request.