PreparationCooking the Beans Rinse and pick over the beans. Place in a medium heavy-bottomed pot with 2 1/2 quarts water, the onion, bell pepper, ajÃes or cubanelle pepper, and the ham hock, if using, and bring to a boil over high heat. Lower the heat to medium and simmer, uncovered, until the beans are tender but still retain their shape, about 2 hours. Drain, reserving 4 cups of the cooking liquid. Discard the vegetables and ham hock; you should have 2 cups cooked beans. Finishing the Dish Place the rice in a medium bowl, cover with cold tap water, and swirl the rice, then drain, holding the rice in place with one hand. Repeat the process as many times as necessary until the water runs clear. Drain well in a sieve or strainer. Heat the oil in the heavy-bottomed pot over medium heat. Add the diced bacon and sauté until golden, about 3 minutes. Add the onion, green pepper, cumin, oregano, and bay leaf and sauté until the onion is soft, about 5 minutes. Add the rice and stir to coat thoroughly. Add the beans and the reserved bean cooking liquid, then add the vinegar, sherry, and salt. Mix well and taste for seasoning; add a dash more of sherry, vinegar, and/or spices if needed. The cooking liquid should be flavorful. Cook, uncovered, until most of the liquid is absorbed and small craters have formed on the surface of the rice. Fluff the rice slightly with a kitchen fork, reduce the heat to the lowest possible setting, and cook, tightly covered, for 20 minutes. Remove from the heat and let stand, uncovered, for at least 10 minutes before serving. Cook's Note: For this recipe the beans do not need to be soaked. The standard procedure is to use the same amount of cooked beans as raw rice, but that ratio can be adjusted to taste. However, if the beans are slightly overcooked, reduce the amount to avoid turning the rice mushy. Cubans have always used Uncle Ben's converted rice because of its low starch content. Working Ahead: The beans may be cooked up to 2 days ahead. Drain them, reserving the cooking liquid, and refrigerate the beans and liquid separately. For a quick fix, this recipe may be prepared with 2 cups canned beans (one 15-ounce can). Drain in a colander set over a bowl, and use the bean broth as part of the liquid called for in the recipe. Recommended Pots: 4- to 5-quart 10- to 12-inch heavy-bottomed pot, at least 3 1/2 inches deep, or 4- to 5-quart 10- to 12-inch cast-aluminum caldero. Reprinted with permission from Gran Cocina Latina: The Food of Latin America by Maricel Presilla, © 2012 Norton