An overnight soak for the beans ensures a creamy texture when cooked with smoky sausage. Slideshow: More Portuguese Recipes
In a large bowl, cover the beans with water by 3 inches and let soak at room temperature overnight. Drain the beans.
In a large heavy pot, heat the oil over medium high heat until hot. Brown the sausage, turning once, until golden, about 5 minutes. Add the tomato paste to the pot and cook, stirring until a few shades darker, 3 to 4 minutes. Stir in the bay leaves, and stock and bring to a boil. Cook until the beans are tender and just starting to fall apart. Season the soup with salt and pepper to taste, then serve.