The day before you plan to make the soup, place the bean mix in a large bowl, add cold water to cover by 2 inches and refrigerate overnight. The next day, drain the beans, rinse under cold running water and drain again. Place the beans in a large pot with 8 cups of cold water. Bring to a boil, lower the heat and simmer for 1 hour. Stir occasionally and skim off any foam that rises to the top. The beans should be very tender and the skin will peel away when you blow on a bean.
Meanwhile, heat the oil in a medium (10-inch) stockpot or Dutch oven over medium heat. Add the pancetta and onion and saute over medium to medium-high heat for 12 to 18 minutes, until browned. Add the garlic and red pepper flakes and saute for one minute. Add the tomatoes, wine, 4 cups of the chicken stock, 1 tablespoon salt and 1 teaspoon black pepper and turn off the heat.
Drain the beans and add two-thirds of them to the soup. Pass the remaining beans through a food mill, discarding the skins. Stir the bean puree and the pasta into the soup, bring to a boil, lower the heat and simmer for 20 to 30 minutes, stirring occasionally, until the pasta is tender. Add up to 2 more cups chicken stock if the soup is too thick. Stir in the Parmesan and the vinegar. Ladle the soup into large shallow bowls and add a swirl of olive oil, a sprinkle of Parmesan and some basil. Serve hot with extra Parmesan on the side.
Photograph by Steve Giralt
You can refrigerate the soup for up to 5 days or freeze up to 6 months. Add more chicken stock or water if the soup is too thick.