For the Beans
1 pound dried cannellini beans
4 bay leaves
2 tablespoons extra-virgin olive oil
½ teaspoon kosher salt
For the Sausage
4 tablespoons extra-virgin olive oil
¾ cup bacon, chopped in 1/2-inch pieces
6 pounds sweet Italian sausage
1 small onion, chopped
2 bay leaves
3 tablespoons tomato paste
2 tablespoons red wine vinegar
2 cups water, hot
3 cups San Marzano tomatoes, crushed by hand
1 teaspoon kosher salt
freshly ground black pepper
Polenta, freshly cooked and soft
Rinse the beans and soak them in plenty of cold water for 8 hours or overnight. Drain and place the beans in a large saucepan with fresh cold water covering them by an inch or more, along with 4 bay leaves and 2 tablespoons olive oil. Bring to a boil, partially cover the pot and adjust the heat to maintain a bubbling simmer. When the beans are almost tender but still slightly undercooked, after about 40 minutes, remove from the heat. Drain through a colander. Stir in the 1/2 teaspoon salt and let cool; discard the bay leaves.
To cook the sausages and tomato sauce, pour the olive oil into the wide saucepan, scatter the bacon pieces and set it over medium-high heat. Cook, stirring, until the bacon starts rendering fat, then drop in the sausages, let them sizzle and begin to brown. Add the chopped onion and the bay leaves, stir them around the pan bottom; meanwhile, keep rolling over the sausages so they color on all sides.
Cook for several minutes while the onions and meat caramelize, then clear a space in the pan bottom and drop in the tomato paste. Stir it in the clear spot for a minute until sizzling, then spread the paste all around the pan, stirring and tumbling the sausages so they're coated. Pour the red wine vinegar into a clear space in the pan, let it sizzle and evaporate for a few moments, then stir and tumble everything again.
Pour a cup of water into the saucepan, raise the heat, and deglaze the caramelization as the water bubbles. Pour in the crushed tomatoes and stir well. Rinse the tomato containers with the second cup of water and pour that in too. Season with 1/2 teaspoon of salt, stir everything together and bring to a boil.
Keep the tomato sauce bubbling gently for about 10 minutes, then spill the beans into the pan. Stir in the beans while the sauce returns to the boil. Stir in water, if needed, so the sauce is loose and nearly covers the sausages and beans. Cook at a gentle boil, stirring now and then, until the beans are tender and the sauce has nicely thickened, 10 minutes or more. (Add water if the beans need longer cooking; or, if the sauce seems too loose, reduce it quickly over high heat.) Turn off the heat and adjust the seasoning with salt and lots of freshly ground black pepper to taste. Cover the pan to keep the beans warm until the polenta is ready to serve.
Meanwhile, cook the polenta according to the recipe, until it is thick, glossy and just starts to pull away from the sides of the pot when stirred, about 30 minutes. For this dish, polenta should be soft rather than dense-add a bit of water and stir well to loosen if necessary. Turn off the heat, remove and discard the bay leaves; taste and add salt if needed.
Assemble individual portions in warm wide pasta bowls. First, dip a large spoon in water, scoop up polenta and mound it in each bowl. Spoon over a generous helping of beans in sauce and lay a sausage on top. Drizzle olive oil over, grind on more black pepper, and serve immediately.