Wash beans, discarding imperfect ones. Cover beans with 2 quarts cold water; refrigerate, covered, overnight. Turn beans and water into a 6-quart kettle. Bring to boiling; reduce heat; simmer covered, half an hour. Drain; reserve liquid. Preheat oven to 300 F.

Trim rind from salt pork. Cut pork almost through at half-inch intervals.

Place sliced onion in bottom of a 3 to 4 quart bean pot or casserole with lid. Add beans; bury pork, cut side down, in center of beans. heat bean liquid to a boiling.

In a large bowl, combine brown sugar, dark molasses, salt and pepper, chili powder, ground mustard, juice from lemons, ketchup and hot sauce. Stir in 1 cup boiling bean liquid. Pour mixture over beans in bean pot or casserole. Lay bacon slices on top. Add more boiling bean liquid to cover beans, up to 1 1/2 cups more.

Bake, covered for 3 hours. (Stir once every hour, so beans cook evenly; add more water if needed) Uncover, bake for an additional hour or more until beans are fork tender.