Re: Chop them under water
"Run tap. Wet onion. Wet knife blade. Cut onion tear-free. Periodically repeat wetting of knife blade."
Same here. A good quality sharp knife and proper steel to keep it honed between uses works wonders. I generally don't even bother with wetting the onion or knife since I'm rarely chopping more than two or three in one session so the job is done before any reaction sets in. It helps doing it by the cooker with the hood extractor fan on too. Just enough of an airflow than any onion fumes are pulled away from me.