Senzu Bean

Senzu Beans are mystical beans with immense rejuvenation properties in the Dragon Ball franchise. 
Senzu Beans are grown by Korin in Korin Tower. When eaten, the consumer's energy and physical health are restored to their fullest; the effects are typically almost instantaneous for the recipient, making these beans a great asset both in and out of battle. Their texture is said to be a cross between an uncooked (or under ripe) bean and a celery stalk, and Yajirobe states that Senzu Beans taste like fish.[1] One bean can keep a person full for ten days,[2] though some who have eaten the beans have become hungry sooner, due to their naturally larger appetite (namely Saiyans as they generally eat much larger amounts of food). It has been seen that eating too many Senzu Beans at a time is dangerous.