Hi Rachna,
 
As the mother of a picky eater, I would agree that balancing "healthy lunch" vs. "what child likes" can definitely be a challenge. However, the two don't have to be mutually exclusive. It is possible to find healthy foods that your child will like.
 
For us, it's a game of "keep trying" and using creative ways to introduce the healthy food (such as calling Brussels sprouts "baby cabbage" or "little cabbages"; or 'hiding' corn or spinach in the middle of biscuits, etc.). We're also not rigid in what we define as "healthy" -- the choices not only limited to veggies, tofu and boring, plain-tasting foods. Pizza can be a healthy option, and it's fun to make with your child too.

As a parent and teacher, I see the battle being won and lost each day. With my child, I prefer sending them to school with lunch. School tray lunches become ala carte for children and the choices are most always bad. I take my kids with me to the store to pick their lunches. We read contents and I steer (not force) my children into the better decisions. I have over the years been able to introduce foods they would have in the past rejected. You won't win every battle, but you'll "win the war". You must have reasonable expectations. Even today I hate Brussel Sprouts. No person will like everything that's good for her/him.