Just one more tip, slicing produces far less airborne onion juice than does chopping. Slicing uses a sliding motion, which separates the onion cells from each other much more cleanly. Chopping, no matter how sharp the knife, crushes some of the onion cells, releasing more micro-droplets into the air.
To dice an onion, I first make a very shallow slice from top to bottom and peel away the first couple of layers to remove the onion skin, and any brown or partially brown layers. I then cut off the bottom and top of the onion. Next, I place the bottom of the onion against the cutting board and make thin, vertical slices from the top, almost to the bottom. I turn the onion 90 degrees and repeat. Finally, cut a thin slice along one edge to make a flat side and place that side against the cutting board. Turn the onion sideways and make thin slices all the way through. This gives you finely diced onion without having to chop and crush the veggie.
This technique also work well for any round veggie or fruit that you want to dice. To control the size of the dice, you simply make the slices closer or further apart. It even works for partially frozen meats, like a boneless ham, or turkey breast.
But remember, your knife must be very sharp at all times. A sharp knife is your best friend, after your spouse and kids of course, and maybe your fishing pole.
Seeeeeeya; Goodweed of the North