Ever since Jerry Seinfeld's wife went on Oprah a while back promoting her cookbook, hiding vegetables in "kid friendly" food has become a popular trend. I don't know about you, but I really don't have the time or desire to cook and puree all sorts of vegetables to put into the meals I'm already cooking and preparing. I also think it defeats the point of encouraging children to eat healthier. How will a child ever learn to like real vegetables if they are constantly being coddled with hidden veggies? How will they ever develop a taste for the real deal?
I have no problem with adding veggies to enhance a food's nutritional value as long as regularly prepared vegetables are also being served. For example, I add spinach to a lot of sauces or I'll make pumpkin pancakes. I'm not trying to trick my children into eating anything, just boosting what I'm already serving.
I'm not a fan of lying to kids to get them to do what you want them to do. They deserve the same respect that adults do. If a child is not told that veggies are hiding in their foods, how will they feel if they find out? They are likely to lose a level of trust and/or not want to eat foods that potentially could be hiding foods they don't like, creating an even pickier child.
In my opinion, the best option is to offer vegetables in their natural form in the most appealing ways possible. Prepare them fresh or frozen by steaming, sauteing, or roasting them for optimal flavor. Offer healthy dips like hummus or top with a little shredded cheese. Serve them in a fun presentation and let the child help in the preparation. Teach them young, and they will develop a healthy relationship with nutritious food without trickery.