For me, it's not just vegetables though they are overall the most challenging category.
I belong to the Picky Eating Adults forum on the web, which is actually how I found this group. I'm really glad to be here!
That group has helped me and also what I have learned to do is what is known as "food chaining," which is to find something you like, and something similar to it that you dislike, and concentrate on the similarities. I did it before I knew what it was called and have learned to like more than one kind of beans that way.
I prefer my vegetables uncooked, usually, or in Chinese food, and I have a terrible aversion to vinegar, so the vinaigrette dressing thing wouldn't be my cup of vinegar, LOL!
But I figure that maybe I get a few bonus nutrients by not cooking the vegetables.
Another thing I found very compelling, though right now I haven't settled down and gotten organized enough to do it, is the idea of using the puree's. Missy Chase Lapine has 3 "Sneaky Chef" books out which I discovered, and Jessica Seinfeld (Jerry's wife) has written a book called Deceptively Delicious
along the same lines. You can even use baby foods as the puree's to save time.
Hope this is helpful, glad to be here, and hope to hear more from fellow veggie challenged dieters!