Look for sweet white runner beans in specialty markets. These are large beans, almost one inch in length. They have a sweet taste and wonderful, creamy texture when cooked. Because of their size, they require a longer cooking time than other dried beans, at least 1 hour, or more if they have been stored for a while. They are the right bean, though, totally compatible with the roasted peppers and fresh rosemary in this recipe. If you cannot find them, great Northern beans are a substitute.