1[Simple pot of Black Beans]
Place the beans in a soup pot and cover with water, plus a few inches. Soak for at least 4 hours or overnight at room temperature. (If your kitchen is very warm, place the beans in the fridge to minimize chances of fermentation.) Drain. You now have 4 cups of soaked beans.
2Return the beans to the pot, add 4½ cups water to cover, plus the garlic. Bring to a boil, and cook at a hard boil for 5 minutes. Skim off any scum that rises to the top. Lower the heat to a simmer and cook, covered, for at least 1 hour, until the beans are tender to the bite. The cooking time will depend on the age of the beans—older beans take longer. Meanwhile, begin working on the sauce (details follow), which takes about 30 minutes and will be ready by the time the beans are done. Season the beans with the salt and remove the garlic cloves.
3[To make the sauce]
Have ready a bowl of ice water. Bring about 3 cups of water to a boil in a medium-size saucepan and add the sweet potato. Return to a boil, cover, and cook for 2 minutes. With a skimmer or sieve with a handle, remove the sweet potato from the pot and transfer to the bowl. Drain and set aside.
4Heat the oil in a deep skillet over medium heat and add the onion. Cook until softened, about 6 minutes. Add the garlic, followed by the cumin, cinnamon, oregano, cayenne, smoked paprika, and salt and stir to combine. The mixture will be pasty. Add the sweet potato, stirring to coat with the aromatics and spices. Cook for an additional 3 to 5 minutes over medium-low heat, allowing the ingredients to get acquainted with one another.
5Add 2 cups of the tomato puree and increase the heat to medium, bringing to a lively simmer. Stir in the tomato paste mixture and chipotle chiles, lower the heat, and cook until well blended, about 10 minutes, stirring regularly to keep from sticking and burning.
6Pour the sweet potato mixture into the beans and stir to combine. Simmer over medium-low heat until you are satisfied with the overall consistency and texture of the chili, about 30 minutes. If the mixture seems too thick, feel free to stir in more tomato puree or water.