I used liquid paraffin on mine.
Go to the chemists and ask for Liquid Paraffin BP, it is medical grade, great for cutting boards and cheap. I gave mine several coats and then finished with a mixture of Liquid Paraffin and Real Beeswax (just warm the two gently together).
You may get some funny looks if you order more than one 150ml bottle (which should be enough), as apparently it is used as a laxative!
I used the "once a day for a week, once a week for a month and once a month forever" routine and my maple and purpleheart cutting board still looks like new.
I would not use Omso Top Oil, I have just used it on an oak worktop and it doesn't smell very natural, certainly not for direct contact with food
hth