How to Dice an Onion

Co-authored by Jillian Fae Downing and Hunter Rising

Last Updated: November 28, 2023 Approved

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Dicing an onion into small, uniform pieces is important in many recipes so they cook evenly. Luckily, there is an easy way to cut your onion so your knife doesn’t slip and so the pieces are all the same size. As long as you have a sharp knife, you’ll have onions that are ready for any recipe!

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Method 1

Method 1 of 3:

Dicing the Onion with a Knife

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1
Cut ¹⁄₂ in (1.3 cm) from the top of the onion. The top of the onion, or the stem, is the pointed end of the bulb. Set your onion on a cutting board, and measure down from the top of the stem by about ¹⁄₂ in (1.3 cm). Use a sharp knife to make a straight cut so you have a flat edge on top of your onion.^{[1]
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- Leave the root on the other side of the onion uncut.
Tip: Sharpen your knife before you start cutting your onion so it’s easier to cut through and to prevent you from getting teary-eyed.
Set your onion down so the side you just cut is face down on your cutting board. Place the blade of your knife in the middle of the root on top and cut straight through the onion so you have 2 halves that are the same size.^{[2]
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3
Peel back the outer skin from each half of the onion. The outer peel usually has a top layer that’s easy to remove and a second layer that’s more difficult to pull off. Rip the loose outer peel off the onion and throw it away. Pick the edge of the next peel with your fingernail to separate it from the rest of the onion. Pull the peel back toward the root without removing it completely.^{[3]
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- The peel still attached to the root can be used as a “handle” to make holding onto your onion easier while you cut it.
4
Cut straight lines toward the root of the onion. Hold your onion by the peel near its root. Start on one side of the onion, placing the tip of your knife ¹⁄₂ in (1.3 cm) from the root. Make vertical cuts from the root toward the flat edge you cut earlier. Work your way across the onion, spacing each cut the same distance apart from one another.^{[4]
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- The root will help hold your onion in place, so be sure not to cut completely through it.^{[5]
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5
Make 2-3 sideways cuts from the flat side. Press down lightly on top of the onion and hold your knife so the blade is parallel to the cutting board. Start cutting into the flat side of onion ¹⁄₂ in (1.3 cm) up from the cutting board. Angle your knife slightly down so you don’t cut toward your fingers. Just before you reach the root, pull your knife out of the onion. When you’re finished with the first cut, make cuts that are the same distance apart until you reach the top of the onion.^{[6]
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- Work slowly so you don’t accidentally cut yourself.
Warning: Don’t put too much pressure on top of the onion while you cut it since it will be more difficult to maneuver your knife.
6
Slice the onion lengthwise to dice it. Turn your onion so the root is on the same side as your non-dominant hand. Put your fingertips on top of the onion so the side of the knife blade touches your knuckles. Starting on the flat side, cut through the onion. After each cut, move your fingers back so you can guide your knife. Make cuts until you reach the root.^{[7]
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- Make sure all of your cuts are the same distance apart so your pieces are all the same size.

Method 2

Method 2 of 3:

Chopping in a Food Processor

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1
Cut the onion in half with a knife. Cut the stem and root off the top and bottom of your onion so you have 2 flat edges. Set the onion upright on one of the flat sides and cut through the middle of it so you have 2 pieces that are about the same size.^{[8]
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- Make sure the chef’s knife you use is sharp or else it will be difficult to cut through your onion.
2
Remove the outer peel from the onion. Use your finger to tear off the loose outer peel from your onion. Pick at the edge of the peel on your onion with your fingernail to separate it. Pull the peel completely off so the surface feels smooth to the touch.^{[9]
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- If you have trouble separating the peel with your fingernail, scrape it with the edge of your knife to lift it.
3
Put the onion halves in your food processor. Take the lid off of your food processor and put the onion halves on opposite sides of the container. Make sure the onions aren’t directly on top of the blades since they won’t dice as well otherwise. Place the lid back on top of the food processor and secure it in place so it doesn’t come off.^{[10]
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- Be careful of the blades while putting your onions into the machine since they are sharp and could cut you.
- Never operate your food processor without the lid.
4
Use the “Pulse” button to dice your onions slowly. Press the “Pulse” button once to start chopping your onions. Watch through the container to see how much it chops your onions. Press and hold the button for 2-3 seconds at a time before letting go so you can see how big the pieces are. Keep pulsing the onions until they’re as small as you need them.^{[11]
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- Be careful not to pulse your onions too much or else they will turn liquidy and you can’t use them in your recipe.
Warning: Food processors won’t chop your onions into pieces that are the same size, so they may cook unevenly.

Method 3

Method 3 of 3:

Using Best Practices

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1
Pick firm onions without any sprouts or soft spots. Look for black or brown spots on the onion peel to see if they’re starting to mold. Avoid buying any onions that have green sprouts growing from them since they are not fresh and are more likely to spoil faster. Look for onions that feel solid and don’t have any discoloration.^{[12]
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- Whole onions stay good in your pantry or fridge for up to 3 months.
Tip: If your onion has a discolored layer inside, you can remove that layer and use the rest of the onion.
2
Chill the onion in your fridge for 15 minutes before cutting it to prevent crying. Onions release a gas when they’re cut open may make you tear up. Put your onion in the fridge or freezer for 15-20 minutes before you want to dice it to help prevent the gas from releasing. That way, you won’t get teary-eyed while you’re working with it.^{[13]
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- You can also wear kitchen goggles to help prevent any tears.
3
Practice safe knife skills. Keep your index finger and your thumb wrapped around the base of the knife and hold the handle securely with the rest of your fingers. Keep the fingers on your other hand in a claw shape so you don’t accidentally cut your fingertips while you’re chopping. When you make your cut, rock your knife forward to get the cleanest cut.^{[14]
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- Always keep the knife blade pointed away from you so you don’t accidentally cut yourself.

Community Q&A

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Question

Should I make horizontal cuts on the onion?

Community Answer

I was always taught to make horizontal cuts first, then the vertical cuts. Also, don't hold the onion like this person. They should have their fingers and thumb "tucked in".

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Question

How can I dice an onion without cutting myself?

Edwin ng

Community Answer

When the knife is close to the side of your hand, move your hand further from the knife.

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