Here’s a handy procedure for chopping an onion, which makes the process fast and easy. It also reduces the likelihood of painful onion tears by locking in most of the fluids during the cutting process. Keeping the root intact throughout cutting helps hold the onion together, making it easier to manage.
Start with an onion.
Cut off the non-root end of the onion.
Stand the onion on the cut side.
Cut it in half through the root.
Remove the onion peel.
Lie the onion on the flat cut side.
Make several vertical slits through the onion, being careful not to cut through the root end. Make the slits close together for a fine dice or farther apart for larger pieces.
Using your fingers to hold the sides of the onion together, carefully make one or two horizontal slits into the onion, being careful not to cut through the root.
Using your fingers to hold the onion together on the sides, cut through the onion, perpendicular to the vertical slits.
Repeat with the other onion half.