Soak pinto beans in water all day.Cook overnight on low in a slow cooker with lots of water. In the morning, drain off most of the water and put in the fridge to cool. Beans should be cold before frying.Add butter or bacon grease to a frying pan.Add cold cooked beans and as much liquid from the beans as desired. The more liquid, the soupier the beans.
Cook on medium heat. While beans are cooking start to mash with a potato masher.
Continue mashing until desired consistency is reached. Ensure that the beans are simmering while being mashed.Add salt to taste.If beans are too runny, then cook a little longer and the liquid will boil off.