What's the best way to cut an onion into chunks before shredding it in the food processor?

I'd cut in half north pole to south pole, then put the halves, standing up, in the feed tube. With my ancient Cuisinart, I'd buy medium sized onions. And I'd try first with the grating blade and then with the slicing blade, if the grating blade cuts the onions into pieces that are just too small. ;o)