The Zen priest literally understood the phrase "hunger is the best sauce."
Although his efforts came to naught, the Zen priest did not feel upset in the slightest.
If you want to be a Zen priest, you have to go through ridiculously tough training.
A Zen priest is a zen priest.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.