It sounds, tbh, as it has only been going on for a couple of weeks and he likes helping to cook that he could just be experimenting with food.
And if he is willing to eat a lot of the things suggested on this thread then he may be getting a more varied diet than a lot or people, including me!
If it continues or he starts to play up well then it may need more serious action but if he is encouraged to try new things, rather than immediately use the "take it or leave it" approach - which may just means he leaves it ! - and helps to cook more etc.. hopefully it will give him a more rounded view of food and eating in general.
And who knows, he may grow up to be the next Heston Blumenthal!