Why Sour Sweet?

The novel that we are reading is titled Sour Sweet. But why? Why did Timothy Mo title this book Sour Sweet? I think that Timothy Mo titled this novel Sour Sweet because he wanted to represent Sweet and Sour which is a cooking methods originated from China, so he wanted to represent food since it is a main part of the book.  Also, I feel like Sour Sweet can also have to do with something being good, but at the same time it being bad. You get a little bit of both and just have to role with the punches. I feel like it is similar in the book when the characters go through times that are sour or rough, but also sweet and nice.