Empty beans in a bowl. Pick out any beans that look bad. Cover with water and soak them overnight.
Next morning dump beans and water into a pot. You can rinse and add more water to beans if you like. Heat beans with the baking soda added to the pot. Reserve the liquid.
Mix 2 cups of reserve liquid with brown sugar, dry mustard and molasses. Set aside.
I use a small crock pot. I layer onions slices, beans and salt pork or bacon ends. Pour reserve liquid and continue to layer till nearly full.
Cover crock with foil and put a cookie sheet on rack below to catch any spills. I add a little extra molasses and brown sugar after an hour or two of cooking. Check beans so they do not dry out and burn. If needed I add some reserve liquid not used in the process.
Oven should be low 250 degrees to 275 degrees max. Cook till beans are tender 5 hours or more.