Before cooking, be sure to pick through them, picking out any small pebbles, split and withered beans and any other foreign matter. (Beans from the Rockies and Pacific coast tend to have more adobe (bits of clay) and stones). It is also helpful to cover the beans with cold water, let sit for 5 minutes and remove anything that floats. Repeat to be sure all dirt and foreign matter is removed. Drain.
Soaking & Cooking
Black beans, like all dried beans, can be soaked before cooking. This hydration helps to reduce the cooking time, but it does effect nutrient content and flavor adversely. Because they are small, 2-4 hours soaking in cold water should suffice. Drain, and cook as per recipe.
If you don’t have the time, boil the beans in water for 1-3 minutes, turn off heat, cover the pot and let them sit for one hour. Drain and proceed as per recipe. However, there is a problem with this quick soaking (boiling for 1-3 minutes) method. Hot water increases the solubility of the water soluble nutrients, and softens the cell membranes of the beans, further accelerating the loss of these nutrients. This should be a consideration, because of the long cooking time during which more nutrients are lost. Cold soaked and cooked at a very gentle simmer, beans retain most of their nutrients, which are considerable.
To cook, drain the soaking water and add cold water, 1 part beans to 2 or 3 parts cold water. Bring to a boil, then reduce heat to a very slow simmer, so the beans stay in their jackets. Simmer for 2 hours.
All legumes are high in protein, and black beans are no exception. Dried beans are important sources of protein in vegetarian diets, and in areas where animal protein is scarce or expensive. However, this protein is incomplete (does not contain all 9 amino acids), so grains (which provide the missing amino acids) must also be a significant part of the strictly vegetarian diet. Or, small amounts of dairy products, meat, poultry or fish (which contain complete proteins) must be part of the diet. In the areas where common beans originated (Central America and southern Mexico) corn supplied the missing amino acids, and squash was an additional source of vitamins.
Black beans, as all dried beans, are also good sources of starches, fiber, B vitamins, iron, zinc, phosphorus, complex carbohydrates and calcium. About half of the calcium is lost during cooking. High percentages of the other nutrients remain however, even after cooking.