2. Drain the beans and transfer to a heavy saucepan. Add the cider and bring slowly to a boil over medium heat. Boil gently, uncovered, for about 30 minutes. Remove from the heat and drain the beans, reserving the cider.
3. Meanwhile, preheat the oven to 300 degrees.
4. Layer half of the salt pork slices on the bottom of a 2-quart ceramic bean pot or other deep baking dish. Spoon the beans into the bean pot, then bury the onions in the beans. In a small saucepan, combine the sorghum, mustard, and salt and place over medium heat to dissolve the mustard and salt. Pour the hot mixture evenly over the beans, and top with the remaining salt pork slices. Pour in the reserved cider and add hot water as needed to cover the beans. Cover the bean pot.
5. Bake for about 4 hours, then uncover the pot and add more water if the beans seem too dry. Re-cover and continue to bake until the beans are tender, 1 to 2 hours longer. The timing will depend upon the age of the beans. Serve hot directly from the pot.
Sandor Katz lives to ferment; it’s his life’s work. The author of The Art of Fermentation shares how to make kombucha at home.