I didn’t appreciate the numerous lovable qualities of dried beans until my college years, when I was living on my own in a house with several other women, all of us strapped for cash. As soon as we discovered that beans are a tasty, economical and nutrient-rich alternative to animal-based protein, they began turning up at the center of our plates with real regularity. Dried beans soaked overnight is the key to this beans and greens gratin.