This is a hearty, rustic dish, which you can vary according to the ingredients you have on hand. It's an adaptation of a recipe from the Moosewood Restaurant Cooks at Home, to which I've added penne, but you could use your favorite chunky pasta. This dish is also one of the few in which I prefer whole-wheat pasta. Any white beans will do, such as great northern, cannellini, navy, or butter beans. Strongly flavored greens, such as escarole, endive, collard greens, etc., contrast nicely with the creamy blandness of the beans, the sourness of the lemon, and the spark of the pepper.