Preheat the oven to Gas Mark 4/180 C/350 F. Heat the oil in a large flameproof casserole and fry the garlic and onion for about 5 minutes or until soft but not brown. Add the pork ribs and cubed pork belly or bacon and cook until brown on all sides. Add the tomatoes, tomato pur?e and stock. Stir carefully and season with salt and pepper. Bring to the boil, then reduce the heat and simmer for about 20 minutes. Meanwhile, if using soaked dried beans, drain them and put them in a saucepan. Cover with fresh water, bring to the boil and boil rapidly for 10 minutes. Drain and add to the casserole. Canned beans may be added without pre-boiling. Transfer the soup to the oven and cook for 1 1/2-2 hours (if dried beans have been used) or until the beans are tender. If canned beans have been used, cook for about 1 hour. Just before serving, toast the bread slices and arrange them in the bottom of a warmed wide serving bowl, or place them in individual soup bowls. Sprinkle with salt and scatter the onion slices on top. Pour the soup over the bread and drizzle with the olive oil, if wished. Grind some pepper over the soup, sprinkle with basil and serve at once.