Peel off the dry outer skin
Cut off the stem end
Leave the root end intact
Slice the onion in half from stem to root
Place one half flat-side down on the cutting board
Make vertical cuts toward the root, stopping before the root
Make horizontal cuts if desired for smaller pieces
Slice crosswise to create even dice
Repeat with the other half
Keep fingers curled inward while holding the onion
Use a sharp knife for cleaner cuts
Work slowly and steadily