Rinse the beans and put them into a large saucepan. Cover with cold water and bring to the boil. Skim the surface of the scum with a slotted spoon. Add 2 whole garlic cloves and one of the sage sprigs. Cook for 1-1½ hours or until the beans are tender. Season with salt and pepper in the last half hour of the cooking time.
In a separate large saucepan, heat the olive oil. Prick the sausa