Place the beans in a large pot with the salt and cover with 2 inches of water. You can either soak them overnight or do a quick soak by bringing to a boil and then turning off the heat and letting them sit for an hour.
After soaking, add to the pot the half onion in the pot and the salt pork. Bring beans to a boil, cover and simmer for an hour, stirring occasionally.
Add the drained cooked beans into the skillet, adding 1/4 cup of the bean broth. Mash the beans with a potato masher, adding more bean broth for desired moisture. Keep stirring the mashed beans in the bacon fat until the texture is a chunky paste. Serve warm.
You can substitute 1/4 cup of lard for the bacon grease. Or you can use 1/4 cup of peanut oil. If you don’t want to cook a pot of beans, 2 (15-ounce) cans of cooked pintos can be used instead.