Place the beans, ham hocks, garlic, bay leaves, and cilantro stems in a large heavy flameproof casserole. Add the water and bring to a boil. Reduce the heat, and simmer until the beans are tender, 1 hour and 20 minutes.
Drain the beans and remove the ham hocks, garlic, bay leaves, and cilantro. Transfer the beans to a food processor, and purée.