I'm having a problem with the whole thing, first of all that does not look like Oak in the photo that I see; it looks more like beech, but it could be the photo quality that I see.
Secondly the function of a food safe oil is to protect the user from any problems that can be given by the wood to the user.
Here you have a nut cracker which cracks nut completely separately from the wood, the bowl will hold the nuts in their shells until you crack them and eat them. I live in the walnut country of France (my neighbour has 150 trees that she harvests each year) , the walnut bowls that they have here are never finished and they don't use a screw cracker, they have exactly the same shape as yours but instead of the cracker there is a mount (raised table) in the centre with a dish shape and they use a mallet to crack the nut (I have made and sold about 50). Unless you are using a toxic wood as a plate from which to eat food regularly as in plate for dinner (ie steak and chips) or plate for soup the need for a food safe finish is minimal and is in some ways a myth developed by many people who have tried to apply the Health and safety laws to a function or situation that does not exist.
I once had a chap try to tell me that removing my riving knife from my table saw was against the health and safety laws.....;. I had to ask him to show me the law.... he tried to do so... I then pointed out that I was a private person at the time and that the title of the law was quite clear it was the health and safety at work act and that it does not apply to people in their own hobbies or homes. Ask any lawyer you wish, it is true; yes you can say its sensible but you may never say that it applies outside of work or in a private home.
Now I am not decrying the act or its intentions, I am just pointing out that it only applies to businesses and is not enforceable to private individuals .... That is the law.