How do you legally charge for an independent contracting service when you don't have a business?

I was recently asked to do a small catering job (less than $700). The issue is that it is for an event at a university and they will only pay a catering company. I would like to help, but after spending a while googling the subject it seems that I need a proper facility approved by the Health Department and a business license. Does anyone know a way around this without having Uncle Sam take an interest in me?