Old-Fashioned Baked Beans

1          lb. Navy Beans, sorted and washed
1/2       lb. side pork (rind removed), diced
1           onion, finely chopped
1/2       cup white sugar
1/2       tsp. dry mustard
1/4       cup ketchup, or to taste
Salt to taste

Place beans in a medium-size kettle, cover with water and soak for 2 hours. Drain beans. Add enough fresh water to cover. Cover kettle, bring to a boil, then simmer until beans are tender. Mix in remaining ingredients. Then place entire contents of kettle in oven proof bean pot with lid. Bake in bean pot at 350°F for approximately 3 hours. (Stir occasionally and add water as needed).