The advice to talk to the admin asst is the best so far. Often these types of interviews will be held in the conference room, with food brought in. We do the same sort of thing, and it's often "boxed lunches" for everyone which means sandwiches and chips. If anyone asks ahead of time though, the same suppliers making 'boxed lunches' - i.e., Briazz or Au Bon Pain - can supply a caesar salad or chefs salad or something. Either way - good restaurant or boxed lunch - this planning ahead is great.

Good luck.