SHELL THE BEANS, rinse them off and put them in a saucepan with water to cover. Bring to a boil for 15 minutes, then drain and return the beans to the pan. Add the oil, onions, tomatoes, paprika, cumin, garlic, 1/2 teaspoon salt, some freshly ground pepper and a cup of water. Cover and cook over a low flame until the beans are tender, about an hour. Taste for salt and add more if necessary. If the tomatoes are too acidic, add enough sugar to balance the flavor. Remove from heat and season to taste with the lemon juice. Turn beans, and their juices, into a serving dish. Garnish with the parsley and cilantro.