The inspiration for this soup was a hunk of butternut squash sitting unused at the bottom of the crisper drawer and a 1-pound bag of dried black beans that came back from one of my "food appreciation" classes.
The more I thought about it, the more I liked the idea of butternut squash and black beans together. My mind has been occupied with Southern food lately, so thoughts naturally drifted toward pork in the soup somehow. I wasn't sure if this was becoming a Southern soup or something Cuban or Caribbean. It just evolved. I stopped at the market for a piece of "smoked butt," something we used to eat all the time when I was a kid. You don't see much mention of it anymore. It's really just a cured ham, but made from the shoulder--or "butt"--end of the pig rather than the hindquarters.
This soup is a two- or three-day affair. Not much work, in fact, but you do need to cook the beans. Pick over a 1-pound bag of dried black beans and remove any stones. Then pour the beans into a large mixing bowl and cover with lots of water. There should be several inches of water over the beans. Let this soak overnight.
The following day, in a large, heavy pot or Dutch oven, saute a large onion, peeled and cut into small dice, along with three or four stalks of celery, peeled to remove the tough fibers and cut into small dice. You can cook this with bacon fat or extra-virgin olive oil. Stir in a teaspoon of coarse salt to season and draw out the juices.
Cook the vegetables over moderately low heat until the onion is tender, about 8 minutes. Place a smoked ham hock in the center of the vegetables along with four thick slices of pork fat back (or "streak-o'-lean) that have been quickly browned in a skillet. Drain the beans and add these plus 3 1/2 quarts water. Make a spice sachet by tying in cheesecloth a fist-full of parsley sprigs, several sprigs of fresh thyme, two or three bay leaves and a half-dozen peppercorns. Use a length of string long enough so that you can tie off one end to the handle of your pot for easy retrieval. Drop the spice sachet into the water, bring the whole thing to a boil, then reduce the heat and simmer, with cover slightly ajar, for about 3 hours, or until the beans are perfectly tender and the soup is redolent of smoked pork.
At this point, I would remove the pot from the heat, cover it completely and let it cure overnight on the stovetop. But you don't have to. The next step is remove the spice sachet, the ham hock and the fat back and run the soup through a food mill or blender until it is smooth and creamy. If it's too thick, add some water. If it seems to thin, cook it some more with the lid off. Then add to the soup 1/2 of a medium butternut squash, skin and seeds removed and cut into medium dice. Also add about 1 pound of smoked butt, cut into medium dice and browned in a skillet for extra flavor.
Bring the soup back to a boil, reduce heat and simmer until the squash is cooked through and tender, about 30 minutes. Do stir the soup frequently, especially around the bottom to prevent the beans from scorching. To finish the soup, stir in 1/2 teaspoon ground coriander and 1 tablespoon molasses. I could also see finishing this bean and squash soup with some balsamic vinegar, some red wine or sherry. There's plenty of room for improvisation.
To serve, ladle into hot, shallow bowls and garnish with chopped cilantro. A slice of buttered corn bread would be perfect on the side.