1.  Place dry beans in a large pot.  Cover them with enough cold water so there is at least three inches of water over the tops of them.  Do not add any salt at this stage or they won’t soften!!  Place over high heat and bring to a full boil.  Turn off the heat, cover and allow the beans to sit for at least 2 hours.
2.  Drain the beans into a strainer and rinse them well with cold water.  Dry off the pot and return it to medium heat.  Add the oil, onion and garlic.  Cook until the onion begins to soften then add any leftover ham, if using.  Cook for about 3 minutes until the ham begins to brown slightly.  Add the beans, ham bone, salt, pepper and red pepper flakes.  Add enough water to cover all the ingredients by 1 inch.  Bring to a full boil, stir well a few times, reduce heat to lowest setting and cover.  Allow the mixture to gently simmer until they have completely cooked and softened, about 3 hours.  Keep an eye on the water level to be sure it doesn’t go below the level of the beans.  If it does, add just enough water to barely cover the ingredients.
3.  If you would like the sauce to thicken more after the beans have softened, remove the cover and continue to simmer for about 30 more minutes.  Or you can mash up some of the beans in the pot to thicken the sauce.  Serve over rice with your favorite toppings such as cheese, sour cream, guacamole, tomatoes, salsa, cilantro and a squeeze of fresh lime.