I read somewhere that putting sparkles on everything works a treat (pun intended!). I don't have kids but from my own experiences as a fussy eater, I had a select few that I would eat: peas and carrots. It wasn't until I left home and decided to be adventurous that I started eating a variety (my mother recently commented that she was shocked I was eating mushrooms!).
I can only suggest that you try finding vegetables that they like the flavour of, then try finding more with a similar taste. If they are fussy, it's going to be a battle of wills and you just need to be patient and persistent