Place beans in a large bowl and cover with water; soak overnight. If you forget to do that, rinse beans well and discard any pebbles before placing them in a pot. Cover with cold water by 2-inches from the top and bring to a boil; cook for 5 minutes and let them sit for 1 hour before draining well.
In a bowl of a slow cooker, combine all the ingredients including drained beans except salt and green onions. Set the temperature on “High” and cook for 7 hours.
One hour before cooking time is over, press about 50% of beans mixture against the sides of the bowl to thicken the sauce with a wooden spoon or a potato masher. Before returning to cook for another hour, add salt and stir. After 7 hours if the consistency is not thick enough, continue cooking for another hour with the lid up.
About 30 minutes before beans are ready, start cooking rice.
When time to serve, place cooked rice in the middle of a bowl, scoop bean mixture around it and sprinkle with green onions. If desired, add a few drops of hot sauce.