Work catering, how to find nutritional informaiton?

I'm good at logging my food from home but when it comes to eating out or catered food I have a total breakdown. I can't seem to get past it. If the restaurant provides nutritional information then there's no problem but if they don't I feel like giving up. Can anyone provide suggestions? I limit eating out to once a week to try and avoid this problem. But today is good example of my work moving to a new location so they had lunch catered. Am I suppose to just try and find a food that is the same or similar and go by that? I'd appreciate any feedback. This is the part of tracking calories I have trouble with.

Thanks!