Expeditions underground can be long and arduous. Many of the wild areas of the world can barely support the wildlife that struggles there, let alone a group of adventurers. So often a party must provision themselves for the long interval between visits to civilization staunchly remaining afloat amidst the chaos of the world.
These rations must last for a long time, be light-weight and nutritious. (Notice the adjective "tasty" was not part of the requirement.) From simple dried fruits and meats, to hardtack, Dwarven Rock Cakes, much sought-after Elvish cakes and Gnomish Energy Pellets; all of these items will keep an adventurer on his feet and ready to face the trials (and trails) ahead.