Basic knife skills: how to dice an onion
To dice an onion, halve it from the tip through the root, peel it, and lay each half flat on the board with the root end still attached to hold the layers. Make a row of lengthwise cuts toward the root without cutting through it, then slice across those cuts to fall into even dice, holding the onion with your fingertips curled under like a claw. Keep the blade moving away from your fingers.
About 15 minutes to learnTake care: injury or damage if careless
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How to do it
- Put a damp paper towel under the cutting board so it cannot slide.
- Sharpen or hone the knife first; a dull blade slips off the skin.
- Cut off the top end, leave the root on, halve the onion from top to root, and peel off the skin.
- Lay one half flat side down, with the root end away from your knife hand.
- Curl the fingertips of your other hand under, knuckles forward, so the blade rests against your knuckles, not your nails.
- Make lengthwise cuts from near the root to the tip, keeping the root intact.
- Slice across the lengthwise cuts toward the root to make dice, moving your claw hand back as you go.
- Discard the root piece and push the dice aside with the back of the blade, not the sharp edge.
Stop and call a professional if
- A cut keeps bleeding after ten minutes of firm pressure, is deep or gaping, or you cannot move the finger normally: get medical care.
Common mistakes
- Holding the onion with fingers flat and extended.
- Cutting off the root first, so the layers fall apart.
- Scraping the board with the sharp edge, which dulls the knife.
- Using a small, dull knife and pressing hard.
Quick self-check
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Teach this to someone
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Teach: Basic knife skills: how to dice an onion
What to say
To dice an onion, halve it from the tip through the root, peel it, and lay each half flat on the board with the root end still attached to hold the layers. Make a row of lengthwise cuts toward the root without cutting through it, then slice across those cuts to fall into even dice, holding the onion with your fingertips curled under like a claw. Keep the blade moving away from your fingers.
What to show, in order
- Put a damp paper towel under the cutting board so it cannot slide.
- Sharpen or hone the knife first; a dull blade slips off the skin.
- Cut off the top end, leave the root on, halve the onion from top to root, and peel off the skin.
- Lay one half flat side down, with the root end away from your knife hand.
- Curl the fingertips of your other hand under, knuckles forward, so the blade rests against your knuckles, not your nails.
- Make lengthwise cuts from near the root to the tip, keeping the root intact.
- Slice across the lengthwise cuts toward the root to make dice, moving your claw hand back as you go.
- Discard the root piece and push the dice aside with the back of the blade, not the sharp edge.
When to stop and call a professional
- A cut keeps bleeding after ten minutes of firm pressure, is deep or gaping, or you cannot move the finger normally: get medical care.
The check question
Ask: Why leave the root on?
Related skills
- How to sharpen a knife
- Five dinners every man should be able to cook
- How to make a pan sauce
- Every skill in Kitchen
Last reviewed . First published .