03Meanwhile, heat the oil in a skillet over medium-high heat. Saute the onion until golden, then add the remaining ingredients except the ham, salt and garnishes. Simmer for three minutes, stirring.04Stir the ham and the contents of the skillet into the beans. Simmer, covered, for two hours, stirring and adding more stock to cover the beans as necessary.05Season with salt and serve with sour cream and sprigs of cilantro