As far as gebrokts, it's very simple, no matza or matza meal in the food. The only possible issue would be if you're worried that someone else is not makpid and you end up with the same plate or bowl that they used the day before for gebrokts.
Don't remember if this was a story or a joke, but I heard (a few years back) that there was a Pesach program that had a waiter walking around the dining hall serving soup.
Waiter: Gebrokts or non-Gebrokts?
Guest 1: non-Gebrokts please.
Waiter pours ladle of soup from serving pot into bowl.
Moves to next guest.Waiter: Gebrokts or non-Gebrokts?
Guest 2: Gebrokts please.
Waiter scoops Matza ball from bottom of said serving pot into bowl, then pours ladle of soup over it.