Clean the beans, removing all stones or chaff. Rinse them well. In a pot large enough to hold the beans plus water to cover, let them soak, overnight.
In a medium size saucepan, over medium heat, saute the salt pork just until it begins to brown. Add the onions and chiles and continue to cook until soft, about 5 to 7 minutes. Add the garlic and continue to cook, about 1 to 2 minutes.
Drain the beans and add fresh water to cover them. Add the contents of the saucepan to the pot of beans. Bring to a boil, then reduce the heat. Simmer, covered, for 1 1/2 hours. Add the salt and simmer, uncovered, for about 30 minutes, or until tender. Watch the beans carefully, and stir once or twice to be sure they do not stick to the bottom of the pan.
Remove 1 cup of the beans, place them in a blender, and blend until smooth. Stir them back into the pot along with the sherry. Add freshly ground black pepper, and serve with Saffron Rice.
Heat the oil in a medium size saucepan, over a medium heat. Add the rice and onion and stir until the grains are coated with oil and the onion is turning translucent. Do not allow the rice to brown. Stir in the salt and saffron, and slowly pour in the water. Cover tightly, and cook over low heat until all the liquid has been absorbed and the rice is tender, about 20 minutes.
Set aside, covered, for 5 minutes. Before serving, stir well to make sure the saffron is well mixed throughout the rice.