It's a sci-fi book and I think the title is "Wanted" or "Wanting" or has one of the words in the full title. Unfortunately, google turned up nothing when I tried both of those words.
Don't remember the full plot, but it's about a man who wakes up with no memory of who he is. All he knows is that he has a sash that indicates he is a gardener. Anyway, the story is about his adventure in the city as he tries to remember his past. He enters paintings, discovers that the city is enclosed in a giant dome, and basically goes through a lot of trouble in order to survive. In one of the paintings, he encounters a girl and her Teacher. Turns out the Teacher is an important government figure who has been putting people through challenging scenarios so that they can develop their survival skills and one day leave the sheltered city.
Any ideas?!