Pick through the black beans and remove any rocks or debris. Rinse and drain them thoroughly several times, then place in a large bowl. Cover with water by at least two inches. My preference is to use filtered or bottled water, rather than tap water, as I use the soaking liquid in the soup.

Let the beans soak for 4 to 6 hours. Keep an eye on the bowl, and top it with water when necessary to keep the beans covered. After the beans have soaked, you can pour away the soaking liquid or use it in your soup. It's up to you. (With filtered water and fresh Rancho Gordo beans, I use the soaking liquid because it has color and flavor).

Heat the oil in a large 4-5 quart Dutch oven or soup pot over medium until the surface shimmers. Add the onions and peppers, and saute for 5 minutes, until the veggies soften. Stir in the cumin, oregano, and garlic.

Push the veggies to one side and add a quick pour of oil to the cleared area. Place the ham hock flattest side down and sear for a minute or two. Use tongs to pick up the ham hock and turn it (and if necessary, hold it) to sear each side that can touch the surface of the pot. Position the ham hock with the most stable side down, and then rearrange the vegetables around it.

Pour the black beans (and the soaking liquid if using) into the pot and raise the heat to high. Top the beans with additional water, covering them by an inch or two. Let the soup come up to a rapid boil and adjust the heat to hold it there. If the pot is spitting water all over the place, back the heat down until the bubbling is behaving in the pot.

Let the soup boil vigorously for about 10 minutes. This, per Rancho Gordo's advice, will help the beans soften faster. Reduce heat and let the soup settle down into lively simmer — still bubbling, but not bursting. Skim off any foam that rises to the surface. Cover the pot with a lid slightly ajar, to allow a little evaporation to occur. From this point, the soup will cook for about two hours.

Check the soup every 20 to 30 minutes, topping with more water* to just cover the beans, and giving everything a good stir, patting the beans down below the water's surface. Replace the lid ajar.

The beans are fully cooked with they mash effortlessly against the sides of the pot with a spoon.

When you reach this point, reduce heat to low, and remove the ham hock. Let it cool until you can handle it, and then remove as much of the meat from the bone as you care to add back to the soup. Much of may have already fallen off, and if that's the case, fish through the soup and cut up any large chunks you find.

Stir in the vinegar and sugar. You can leave the soup completely chunky, or blend some or all of it to a smoother texture. For my preferences, I like lots of whole beans in a thick base, so I remove a cup or two of the soup to a large bowl and blend it smooth with an immersion blender. Doing this separately, outside of the pot, provides better control, as sometimes an efficient immersion blender will very quickly push too many beans through its blades! You can also use a traditional blender.

Now carefully taste the soup — it's still hot, spoon some out and let it cool. It probably won't need seasoning, but add more salt if you like. And if the soup needs a little more brightening, squeeze a little fresh lime juice into the pot.