Tenzo is one of the positions in a Zen temple.
It's the fifth position of the rokuchiji ("six officers" of a Zen monastery)
Tenzo is a position in charge of cooking meals for ascetic monks, as well as of serving trays of offerings for Buddha statues and the founder of the sect.
Although people in general society may look down upon the cook and think of the work as a background job, the position of cook is considered important in Zen temples because cooking and eating meals are also regarded as important aspects of training, and the cook is a position that can do intoku (do good in secret without expecting a reward). It is said that an experienced, sincere and well-tempered person is often appointed as the tenzo, and that many tenzos are highly prized as advisers to monks.
The Soto sect tells of a historical event in which, when the founder Dogen was training in Song (Dynasty) to seek the teaching of Buddhism, he met with two tenzos and thereupon recognized the essence of the Zen training. Thus it's traditional in the Soto sect that the position of tenzo is highly respected, based on this event.