Prepare and cook the beans: Soak dry beans in water overnight.
In the morning, drain the beans, place them in a medium pot full of cold water, cover, bring to a boil, and then reduce to a gentle simmer for an hour until beans are fork tender but not mushy. Drain and rinse the cooked beans with cold water. Set aside.
Make the BBQ sauce: In a heavy-bottom Dutch oven, sauté the bacon and onion for 5 minutes until the onion is translucent.
Add the remaining ingredients (salt, pepper, mustard powder, molasses, brown sugar, ketchup, and water) to the DO with the onion and bacon and bring to a boil, stirring occasionally.
Bake the beans: Add the cooked beans to the boiling barbecue sauce, stir, and remove from the heat.
Cover with a lid and bake at 275 for 5-6 hours. Stir every 30 minutes and add a few tablespoons of water if the beans begin to look dry at any point.
Serve hot.