Lay the beans on a large baking sheet to check for stones and rocks.
Rinse the beans in a colander and then dump into a large pot.
Add two quarts of water, the onion and two tablespoons vegetable oil. Bring the water to a boil.
Transfer the beans and water into your slow cooker and cook on high for 6 hours. When the beans are tender, stir in 1½ tablespoons salt.
At this point you can smash them and just have smashed beans, or you can fry them up in a bit of garlic and bacon grease and have heaven here on earth. (If you need, you can refrigerate the beans after they have cooked in the crock-pot and save the frying and smashing for day two.)
To fry them, heat vegetable oil or bacon drippings over medium heat in a large pan. Add the garlic and stir until the garlic is fragrant, about one minute.
Add the beans and enough water to cover the beans. Bring to a simmer and start to smash the beans with a potato masher. Continue to smash and stir for 5-10 minutes until the beans are the consistency of soft mashed potatoes. Don’t over cook or the beans will get dried out. Salt to taste.
Remove from the heat and enjoy.