Black Bean Soup with Apple

8 cups water
1 pound dried black (turtle) beans (about 2 cups)
6 ounces smoked bacon (6 slices), very finely chopped
1 large onion, finely chopped
5 cloves garlic, finely chopped
4 ribs celery, finely chopped
7 cups unsalted chicken stock
1/2 teaspoon dried red pepper flakes or cayenne powder
2 teaspoons ground allspice
1 teaspoon ground ginger
5 fresh (or 3 dried) bay leaves
2 large tart apples, peeled, cored, and cut into 1/4-inch dice
1 tablespoon finely chopped fresh thyme
1 tablespoon finely chopped fresh rosemary
1 1/2 teaspoons salt
Freshly ground black pepper to taste
2 teaspoons sherry vinegar or apple cider vinegar
2 tablespoons pure maple syrup or dark brown sugar
Optional garnishes: chopped chives or green onions, and/or shredded sharp Cheddar cheese

Early in the day or a day ahead: 
Bring the water to a boil in a large (6- to 8-quart) soup pot.  Pour in the beans, remove the pan from the heat, and let the beans soak for 1 hour at room temperature or overnight in the refrigerator.  Drain the beans in a colander and rinse them thoroughly with cold water.

Rinse and dry the soup pot and place it over medium heat.  Add the bacon and cook, stirring often, until it renders most of its fat but is not quite crisp.  Tilt the pot and use a large spoon to remove some of the fat if needed, leaving about 1/4 cup behind.  Add the onion, garlic, and celery; cook, stirring often, until they are softened, about 5 minutes.  Add the beans, chicken stock, pepper flakes or cayenne, allspice, ginger, and bay leaves, and bring the mixture to a boil.  Reduce the heat, cover, and gently simmer until the beans are very soft, about 1 1/2 to 2 hours.

Stir in the diced apples, thyme, rosemary, salt, black pepper, vinegar, and syrup or sugar.  Simmer the soup until the apples are very soft but still hold their shape, about 15 minutes.  Remove the bay leaves.  Taste and add more salt or vinegar if needed.  For a creamier texture, partially mash the beans with a potato masher or handheld immersion blender.  

Serve with chives or green onions, and/or sharp Cheddar cheese.

Serves 8.

From The Herbfarm Cookbook by Jerry Traunfeld, with minor changes

Note: For a vegetarian version, substitute 1/4 cup olive oil for bacon and use vegetable stock instead of chicken stock.