Black beans are a go-to side dish for any Baja meal.
Place beans in a large bowl or stockpot; cover with cold water by 2 inches. Let stand at room temperature 4 hours or overnight. Drain, and rinse beans with cold water; set aside.
Heat the oil in a large saucepan over medium heat. Add onion, and cook until it is soft and translucent but not browned, about 8 minutes. Add the beans and the cold water, along with the orange peel and/or jalapeno, if desired. Bring to a boil, and reduce heat to a gentle simmer; cover, and cook, stirring occasionally, until the beans are tender and most of the liquid has evaporated, creating a saucelike consistency, about 2 hours. Most of the liquid should have evaporated.
Remove from heat; remove orange peel and/or jalapeno, if using. Season with salt, black pepper, and hot-pepper sauce, if desired. Serve hot or at room temperature.