I tempted my son with mobile phone while feeding the food the refuse to take. It works most the time.

My son is still a prickly eater. He is a very rigid person himself. We improve the situation with exposure and also slowly introduce/add in new food to its existing food. As such cocoa krunch into cornflakes, soy milk to replace current cow's milk, add in new vege (very little amount at first) into his rice etc.