Place the beans in a large colander and sort through them to remove and discard any stones or debris.
Rinse the beans and transfer them to a large pot or Dutch oven. Add the water, cumin, olive oil, salt, and pepper and bring to a boil. Reduce the heat, add the kombu, if using, and simmer, uncovered, until the beans are tender. I like to check mine starting at 1 hour, and every 15 minutes after that. Depending on your freshness of your beans, it could take up to 2½ hours. Add more liquid to the pot, as needed, to keep your beans submerged.
Remove the kombu and add the garlic during the last few minutes of cooking.
Season the beans as you like, adding chili powder, oregano, and more salt and pepper, if desired. Let the beans cool in the cooking liquid (I like how it gets nice and thick). Just before serving, stir in lime juice, zest, and cilantro, if desired.