These are not a bean unto themselves, rather they are a part of the huge New World bean family Phaseolus, also known as Common Beans. I have previously written about the genus last year as a Harvest Ingredient. They are not be be confused with the Douchi, beans that go into Chinese Black Bean Sauce. These New World beauties are most commonly called "Black Turtle Beans," and are thought to originate in the Andes, were the first evidence of common beans being cultivated dates back thousands of years. Today they are cultivated in both South and North America, with their nexus lies in Meso-America, present day Mexico and upper Central America. They are indispensable in ancient and modern day Maya cooking! But they are also commonly cooked and consumed in great amounts in the Caribbean as well. Cubans would be lost without them! They are also an indispensable ingredient in the Brazilian Feijoada. Amongst modern cultivars some varieties include Zorro, Black Magic, Domino and Blackhawk (which is, presumably, named for the great Sauk leader Chief Black Hawk of the Sac & Fox). In native communities varieties can be found amongst the Hopi, the Cherokee (which is a type of yellow wax bean, and was eaten a lot in it's immature stage, the beans themselves look like black kidney beans and are sometimes called Trail Of Tears Bean), the Tarahumara of northern Mexico--who grow at least three varieties, the Conchos of Chihuahua, there is even a black tepary bean, found in the Zapotec and Mixtec areas of Oaxaca.
All common beans are an excellent source of protein, and paired with corn make a perfect protein. They are also popularly served in combination with rice, which also comes close to a perfect protein. Black Beans are also high in Vitamin A, Folate (a B vitamin) and Omega 6 & 3 fatty acids; additionally they are a great source for Phosphorus and Potassium and a fair source of Magnesium & Calcium. There has been quite a lot of research done recently on black beans to discover additional nutrients, and they have been found to benefit the colon in the form of probiotics, and that they rival, and in many cases surpass, "colored vegetables" like carrots and beets in Phytonutrients. New research has also found, and this is a big one for me, that soaking them increases their nutritional value. This same research also shows that soaking them and then discarding the soaking water provides the most nutrients and reduces the compounds that cause flatulence. So recipes that call for keeping the water seem to be on the wrong side of things when it comes to the science of nutrition (which means that traditional modern Maya families, who religiously retain the soaking water are as well). Also seriously on the wrong side of this research are people like me who don't soak at all....so next time I will.
In addition to the preparations mentioned above, black beans are most often cooked as "pot beans" (frijoles olla) and served with a bread of some sort, or put into Black Bean Soup, but also show up in Chili. In parts of Mexico and Central America, they are also mashed, and sometimes fried to make a side dish or a dip to Totopos (fried tortilla pieces). The the Guatemala highlands, they are mashed and put into tamales, the most special of which is called "Ooben" in the Ixil language of Nebaj. Native household in the southeastern US make them into cakes that are typically fried in bacon grease. They are also popular made into a salad, especially with corn or as part of a 3 or 4 bean salad. In the southwest they are tucked into burritos, enchiladas, quesadillas or as topping for a vegetarian version of the standard "Indian Taco." For a Meatless Monday entree, they are made into bean burgers and in the Andes, where they most likely originated, they are served with the "Incan" ultra "grain" quinoa. Further, they have become a popular ingredient in salsas. In the Philippines, they sometimes show up in a crazy shave ice dessert called Halo-Halo.
Internationally they are sometimes show up as a pasta topping or even in lasagna. In China, which is now the largest producer of the New World black bean, they are put into steamed dumplings and some types of stir-fries; they are also eaten fresh from the vine, simply cooked by themselves in many rural households. In North Africa, they show up with couscous and in the Middle East, they are sometimes used like Fava beans in "Foul" or foul mademas or put into hummus with Tahina. In India (also a huge supplier), they are put in curries and used like other dal in various spice mixtures. In Spain, where they first showed up on the international table, they are cooked with well cured and dried Spanish style chorizo (it's a bit like hot pepperoni). Recently they have been used as a base in sweets, like brownies.