Nobunaga was known to love strong flavored country foods. According to the Shincho-Ko ki, he ate melons, persimmons, chestnuts, and crammed rice cakes (mochi) in his mouth. There was a story that Nobunaga almost killed a cook because the food was not up to his tastes.
It was well know Nobunaga ate some form of chazuke (rice porridge) before the Battle of Okehazama. Simple country foods, strong flavor, and packed with nutrients kept Nobunaga healthily and stable.
A great link with some information in English on Nobunaga and his diet:
According to the link, he was also fond of dumplings and were nicknamed "Uesama dango" (His Highness's dumplings). Perfect and fit for a king. Of course, on certain occasions, the food would be more elaborate.
Nobunaga no tame!