I don't know whether this was the right thing to do or not, but dd1 used to be (well, still is really!) very fussy, and I used to mix banana with just about anything to get her to have more variety in her diet. She also liked peaches, so I would mix peaches with other foods (yes, including meats!).
I know this technique did not help her to like other foods (as she couldn't taste them) but she really just would not eat a lot of things, and I worried about her iron intake etc.