Place the dried beans into a Dutch oven with 6 cups (1.5 L) of water. Soak overnight.

Drain and pour beans back into the pot with enough water to cover the beans by a couple of inches, cook for 30 minutes until they are tender but still firm. Drain beans, making sure to reserve cooking liquid, set aside.

Preheat the oven to 325 °F (160 °C). While the oven is preheating, cook pork over medium-high heat in the Dutch Oven until fat is rendered and pork is beginning to brown, then add the onion cooking until tender.

Add the beans back to the pot, along with molasses, brown sugar, apple cider vinegar, ground mustard, salt and pepper and 3 cups (750 mL) of reserved bean water.

Bake uncovered for 3 to 5 hours until the beans are tender, and the sauce has thickened, and the edges of the pot get sticky.

(Note: if beans get dry, add another cup of water.)