I want a vegan to pay for their food at my barbecue.
Why would you want to force someone to pay for their own food just because they're vegan?
I want to teach her a lesson for making me cook something she doesn't even want to eat.
The person who is vegan could be doing it for a good cause, like being against animal cruelty. They shouldn't be treated differently just because they don't want to eat bar-be-cue and you should be respectful of her wishes.
WTF are you trying to pull with your logic? You make no sense. Let's go on Facebook and write an insult about her and call her a cunt.
It isn't too hard to make a small change or buy a pack of frozen veggie burgers for her. You really don't have to go that far out of the way. Don't you also think it is rude to make someone pay if they are a guest?