2 T raw apple cider vinegar
Water to cover by 3 inches
Soak beans in water and vinegar for 24 hours. It is normal for bubbles to form on the surface of the water.
Drain beans, add to a large pot, cover with water by at least an inch.
Bring to a boil. Skim foam, then simmer until beans are tender. Depending on the bean, between 1 and 2 hours.
Drain cooking liquid and use now, or freeze for use later.
See "Awesome Black Beans" for a really great variation.