This is an old recipe that I got from my mother, she never made it when I was younger because she doesn't like sweet potatoes. I have made this recipe now quite a few times and it always turns out moist and delicious. The mustard is optional, and I leave that out as my family doesn't like mustard, although I think it still tastes good with it. The sauce at the end is also optional, I have eaten it before without the sauce and it is still wonderful. The sauce adds a little extra touch though, but use it sparingly, or it will really overpower the great taste of the pork.