Here are some things I might like to write a book on:

Workhouses

Public grief ceremonies

Gypsies

magic realism

mythology and folk tales

Is punishment more terrifying when you know exactly what's going to happen, or when you face the unknown? Lots of people starved to death (unknown) rather than go to a workhouse (known). You'd think it would be the other way round.

steampunks

I am surprising myself in that I have no desire at all to write about food. No desire to write about eating disorders, or theatre, or anything that I usually read about. I might write on facial modification though. If you could modify your face, how would you tell that someone was really them? What if the face was modified but you had to act exactly the same in every circumstance.