Ignoring it is what I usually do. I mean, I don’t go out telling I’m vegan unless I have to for some reason. If I don’t say anything, they won’t know. If I know the people I’m around with are mean/ignorant/close-minded people, I’ll never mention about the fact that I’m vegan.
I’ve had this problem too, and I’m from Michigan. I think the best way to handle it is to be polite. Kindly tell the person that their opinion isn’t wanted, and if they have any questions or would like to understand why you chose alternative eating styles, you’re always willing to answer their questions. Most people, my family included, just thought it was weird and didn’t understand it. Once you explain and keep doing what you’re doing, they’ll eventually leave you alone about it, or grow more interested.
Kill them (metaphorically!) with kindness!
In my own experience, getting angry just makes people continue to mock and tease but if you take a deep breath, smile and respond with something polite then they don’t feel they’re ‘winning’.