We mainly do events/festivals. No HD approval needed and the money is under the radar. You can Google search a city name and add festival to it. Sometimes you get lucky and you will find a direct link to the festival website.  If you do events that you receive payment from you might find a 1099 form in your mailbox at tax time if you received $600 or more.
Don t get us wrong, we are not endorsing operating a business illegally. Unfortunately our system seems to squash the small entrepreneurial spirit that made this county.  States like ours won t even allow you to share commercial kitchen space. Some states have requirements that make it almost impossible to operate legally.
The events/festivals we do often state in the rules that no HD approval is required and only ask that you use a common sense approach to food safety. The only drawback is that there are a lot of people who try to cash in on the events. On the plus side is that when they realize how little they actually make they quit.