If they would just TRY the quinoa salad! It has always been the case that adults have to rather pressure kids to eat things that are good for them. I don’t know how many times my mother said “Oh just try it, for Pete’s sake, it isn’t going to kill you!” Because left to my own devices, I’d have lived on cinnamon PopTarts and PB&J.
However, you still have to get past two things:
The fact is that if you tell a kid something is "good for them", they'll starve before they eat it.
If they give in and try it, the rest will be howling "Eeewwwwww!" or noises to that effect, and they'll likely not eat any more.
Pity to end up with that much food in the trash, but that is a predictable result.
Few will get any epicurean exposure at home beyond a new flavor of Chef Boy-ar-dee... and the unfamiliar rarely stands a chance.
One more thing: Kids and adults have different tastes insofar as what to eat, and kids have different nutritional needs. They are still building their bodies and as such will crave different foods at different times in that development. Adults are maintaining an existing structure, and they crave different foods.