The thing that finally got my dragon to eat veggies was the use of a green food dish for his superworms. He now will only eat green veggies but luckily collard greens and green beans are green and he loves green beans. I'm not sure if it would be easy (or successful) to do that but other things you could try is rolling up the veggies to look like worms, moving them around, or putting some in his mouth as he licks his chops to have him try it, and just being persistent.
good luck