Many different types of food and drink are mentioned throughout the Chronicles of Narnia. For the most part, Narnians appear to eat very well: Long lists of delicacies are seen throughout the series, and descriptions of meals, both simple and elaborate, are common features as well.
As a plot device
Aside from adding imagery to the stories, these extensive descriptions of food and drink sometimes serve another purpose; they help to contextualize the scene in which they appear. The specific types of foods mentioned, their quality and quantity, which characters consume them, and even how they are presented and served often reflect some aspect of the larger picture:
Displaying diversity of creatures
The many creatures and species of Narnia favored different types of foods according to their nature. For example, the tree people consumed numerous varieties of earth and soil, as opposed to foods favored by the more "humanoid" types of creatures. Centaurs, meanwhile, had to consume foods that satisfied both their man-stomachs (porridge, cooked meats, and toasted bread) and their horse-stomach (grass, raw oats, and sugar).
Highlighting differences between regions
Shasta's experiences in and around Tashbaan not only showcased the richness and variety of Calormene cuisine, but featured a host of exotic foods rarely seen in other regions of the world, such as lobsters, melons, rice, and unique desserts.
Reflecting circumstances and situations
When characters were in the middle of difficult situations, or in the presence of evil, the food in these scenes tended to be spartan and/or low in quality: When Edmund is at the White Witch's castle, he expected Turkish Delight, but was served only water and dry bread; when Jill, Eustace and Puddleglum were taken hostage by the gnomes in Underland, they were fed bland, tasteless cakes; and when Jill and Eustace first took refugee with King Tirian, the only food available was porridge made from crumbled biscuits.
By contrast, when a victory had been achieved or a mission had been completed, the food served afterwards was typically delicious. After defeating the Telmarines, the Old Narnians were treated to an especially lavish feast, which included meats, fruits, and many different kinds of wine.