To cook the beans, pick them over, rinse well, place in a bowl with water to cover generously, and soak overnight. The next day, drain the beans and place in a saucepan with the 2 quarts water. Bring to a boil over medium-high heat, reduce the heat to low, cover, and simmer until tender but not soft, about 40 minutes. Add 1 teaspoon of the salt during the last 15 minutes of cooking. Remove from the heat and set aside.
Combine the garlic, rosemary, the remaining 1½ teaspoons salt, the 1 teaspoon pepper, and red pepper flakes to taste in a bowl. Heat the olive oil in a large sauté pan over high heat. Add the pork pieces, in batches, and stir until golden, 8 to 10 minutes. Sprinkle the browned meat with the garlic mixture and the lemon juice and stir well to coat with the spices. Reduce the heat to low, cover, and cook until the meat is tender, 45 to 60 minutes. According to the original recipe, while the meat cooks, you must keep “draining the fat as it accumulates in the pan and reserving it.” Most pork sold in the United States today is quite lean, however, and does not give off much fat, so keep whatever it does give off in the pan with the meat. If the meat seems dry or starts to stick, add a bit of water or stock.
If when the pork is done, there is extra fat in the pan, spoon it into a large saucepan and use it to warm the cooked beans. Otherwise reheat the beans over low heat in their own liquid. Transfer the beans to a large serving dish and sprinkle with lots of black pepper and pecorino cheese. Spoon the pork over the beans and serve. Alternatively, combine the pork and beans in a pot and heat together to serving temperature, then transfer to a serving dish and sprinkle with the pepper and cheese. Serve the stew hot or warm.