Boiling the beans with a bay leaf and fresh oregano will infuse the beans with an earthy flavor that takes this simple dish to the next level.
If using dry beans. Sort through beans, discarding any small stones, then rinse under cold running water.
Put beans, bay leaf, oregano, and 1 tbsp. of the oil into a large pot, then cover with cold water by 3. Bring to a boil over high heat, then reduce heat to medium-low, and simmer, adding more water as needed to keep beans covered, until beans are tender, about 2 hours.
Heat remaining 3 tbsp. of the oil in a small skillet over medium heat. Add cumin, scallions, garlic, and green peppers, and sauté, stirring often, until peppers are soft and scallions are golden, about 10 minutes.
Season to taste with salt and pepper, then add to beans. Continue cooking beans, stirring occasionally, for 10-15 minutes. Adjust seasonings. Remove bay leaf before serving. Serve with rice, if you like.