Little children have a natural tendency of resisting vegetables :) no matter how hungry they are they always prefer anything over a cucumber or broccoli.
The one reason is probably the poor presentation of those beneficial vegetable which work as building block in kid's growth.
Here you can do some nice idea. Use the stainless steel coocie cutter and shape the vegetables in to assorted stars and flowers. Now young one will be more interested to take a bite , NO ?
You can buy those cutter from local store or better can buy online from Amazon.