Food
In Land of Milk and Honey, food is symbolic of life. People eat food to provide them with nourishment; when they don't have enough food, they invariably die. As climate change ravishes the earth in Zhang's novel, food becomes increasingly harder to grow and much more scarce. Food becomes as good as gold.
The chef
The novel's main character, the female chef who goes to work for a wealthy family in an isolated family, is symbolic of the way that many working-class people are forced to operate in a different world than their own. The chef left an environment in which she only had basic ingredients at her disposal—and sometimes not enough of those ingredients. When she goes to work with the wealthy family, she is transported into the past. She has access to rare ingredients and a good quality of life. This new world shocks the chef, but she is honored to work in such a unique environment—even though it is so different than her own world.
Smog
The smog which has blanketed the earth is symbolic of the way that humans have destroyed their world. Through global climate change (which was instigated by human behavior), a layer of smog emerged across the world, hurting people and causing society to crumble.
Violence
As the chef becomes more deeply entrenched in the world of her bosses, a motif of violence emerges. Her bosses and their community use violence as a way to control those around them—especially those who are not in a great financial situation.