A food ration is the most basic comestible in NetHack. Many roles start out with a number of these. Samurai know them as gunyoki. They provide enough nutrition to fill you when you are hungry. They are also suitable for vegans.
Note that a lembas wafer provides the same nutrition as a food ration but is much lighter.
Encyclopedia entry (gunyoki) Edit
The samurai's last meal before battle. It was usually made
up of cooked chestnuts, dried seaweed, and sake.