...never tell your kids to get them to try a food
1) There are starving children in ______ (Africa, China, Somalia, Mars, etc). This isn't going to mean a thing to most kids because faced with a plate of something they consider to be too gross to eat, they'll choose starvation at least temporarily. And since most kids have never come anywhere close to starvation themselves, they have no idea what you are talking about anyway. Besides, that's so 80's.
2) It's better than what they would serve you on Fear Factor. This isn't going to work because Fear Factor isn't on anymore and even if it were, would you REALLY be letting your small child watch it? (If the answer is yes, you can stop reading now, I can't help you.) Second, Fear Factor contestants are trying to win $50,000. Unless you are willing to pony up some serious cash, this argument is now invalid. And if you are wiling to pony up the cash, you're creating way more problems than you are solving.
3) You are going to sit there until you try it. Encouraging a stand off is a sure fire way to make sure everyone loses. If you have a particularly stubborn child, prepare to be at that table with them for a while; possibly until the next meal, and possibly until the next morning. And you and I both know you have better things to do. Like watch paint dry.