re: Introducing Children To Fine Dining.

I absolutely applaud you exposing them to it early on though. There was nothing I hated more than being in Jr. High/High School and having friends who refused to order anything other than chicken tenders at restaurants.

You have no idea how many homecomings were spent at Chili's when I was in HS.

*Now that I read the responses, I agree to exposing it in the home. It sounds like your children already eat a different diet than the average child, so they might possibly enjoy the night out somewhere different.
If it were me, I'd probably talk about it a day or so in advance like it's something exciting. Make it to where they can't wait to go and eat this yummy food. If you make it out to be something exciting and rare, they might get excited themselves and try the food fearlessly.