I suppose I could have done this with my router planer and some clamps to hold it in place, but I was feeling kinda stubborn with this piece. The process illustrated below has been in use by others for a very long time, so I just had to try it myself. I must say, it performed well, and the piece turned out to be the centerpiece at the wedding of our friend's daughter's head table. Not bad for a piece of charred, faded, gnarly firewood.
And this is what the finished product looked like front and back: