Vintners acknowledge the influence of the soil in which a vine is grown on the taste of the grape, and thus the taste of the wine. Terroir--loosely translatable as "sense of place"--matters in tangible, taste-able terms.
Third culture authors are not alone in their interest in food, nor is their acknowledgement that food is an essential part of culture, of what makes home. Home has a taste: literature writes about it over and over again.
Perhaps, though, third culture authors are more highly attuned than most to conflicts between the soil and the food. Kingsolver's Nathan Price (The Poisonwood Bible) plants a lavish vegetable garden that won't grow in the Belgian Congo because there are no pollinators for the American plants. In Alison's Natives and Exotics (which uses imported plants as a metaphor for dislocated people) a grove of orange trees dies of an imported blight.
In Lively's The Photograph a prominent character is a gardener who derides the recent vogue for imported pampas grasses . . . she too is aware of what is native and what is not.
TCKs are famously non-judgmental. All that cultural awareness makes us open-minded. Except, perhaps in the matter of food? I wonder if this is one area in which we allow ourselves to taste authenticity, belonging and terroir, and deride imports.