I didn't eat solid food until I was 18 years old. I lived on baby rusks and pureed Sunday dinner and survived. I'm 38 now and I love food. It worried my parents and they tried everything to help, which stressed them out even more. I have Apergers but was only diagnosed as an adult.
My advice is to take the pressure off and the child will eventually explore and experiment with food by themselves and probably find they quite like it. The weaning process takes far longer than with a 'normal' child but they won't starve. Children can thrive on what seems a very restricted diet. They're not doing it to annoy you but the more it does the harder it is for them to try anything new so just relax and go with the flow.