Hi Paul, Bryan has it about covered, I was about to reply with the following, his post beat me...
Oak if dry can be hard to get a go finishing cut and sanding may not clean up every bit, there's a little patch on the inside in the end grain which looks like dust filled grain tearout, is it so, as it's still mounted can you try an remove it with a fresh ground sharp gouge, you look to have a step a little way down from the rim, you could work from there with the clean up of the grain, your rim looks as if it has a double edge.
For a finish you could use Danish Oil, even a thin coat to help final sanding will lift the grain and show any marks missed, wipe clean and apply Oil to what you what as a finish, wiping dry between coats.
Look forward to see it finished.
Cheers David