After sanding and all that - you use a food grade mineral oil, or just a vegetable oil. I just got a small wood cutting board from IKEA with the instructions to oil the finished board twice. Oil the board, wipe off excess, let stand overnight. Repeat.
I did it 3 times and the oil was still soaking into the wood.
You can also use this to recondition a wood cutting board, optionally lightly sand it first.
NEVER clean it in the dishwasher or let it sit in water...
Have fun with this!