Preheat oven to 350 F. Boil sweet potatoes until tender but still firm and allow them to cool. Then peel, slice, and place in a shallow baking dish. Core and slice the apples, then sprinkle salt and lemon juice over them. In a skillet bring butter to a slow sizzle and toss apple slices around in the pan until slightly soft. Arrange apples with the sweet potatoes. Then add molasses to butter remaining in pan and bring to a boil. Pour over apples and sweet potatoes, coating well. Sprinkle brown sugar and pecans on top. Bake for 30 mins or until brown and bubbly on top.