How to Slice an Onion

Step by step instructions on how to safely slice onions both lengthwise, and crosswise.

You can either slice an onion lengthwise, from stem to root, or crosswise. If you are slicing the onions to cook them, as for making caramelized onions, it's best to slice them lengthwise, or from stem to root. This way the onion holds its shape better during long cooking. To slice an onion to be used raw in a salad or a sandwich, you can halve it and then cut it crosswise, for pretty, half moon shapes, or you can keep the onion whole and slice it crosswise for onion rings.

  • Prep time: 2 minutes


  • 1 onion, any color—red, yellow, white


Method for Slicing an Onion from Stem to Root (for cooking)

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1 Cut off the stem end of the onion, by about 1/4 to 1/2 an inch.

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2 Cut off the roots, but keep the root end intact. An intact root end will help hold the onion together as you make the other cuts.

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3 Place the onion with the cut stem side down on the cutting board. This will stabilize the onion. Cut the onion in half through the root end.

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4 Peel back the onion skin and place the onion halves cut side down on the board. If you want, to help keep your cutting area tidy, peel off or cut off the onion skin from the root end.

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5 Cutting along the natural lines of the onion, make angled cuts into the onion, aimed at the center of the onion. Cut almost all the way, but not all the way, to the root. It will be easier to handle the onion while cutting if the root end stays intact. Space your cuts depending on how thick you want your onion slices to be. More cuts for thinner slices, fewer cuts for thicker slices.

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6 Cut a "V" in the root end to cut away the tough root end that is holding the onion slices together.



Method for Slicing an Onion Crosswise (for serving raw in salads or sandwiches)

1 Cut off the stem end, place the onion cut side down on the cutting board, cut it in half through the root, and peel back the skins as in steps 1 and 2 above. Do not remove the skins. Place the onion halves cut side down on the cutting board.

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2 Hold the onion firmly with one hand, with the fingers curled inward. With a sharp chef's knife in the other hand, place the side of the blade against the knuckles of your index and middle fingers. Use this as a guide as you make slices through the onion. The curled fingers will protect your fingertips from the knife while cutting the onion. When you get close to the root end, you can hold on to the peeled back skins as you make the final cuts in the onion.

Here's a tip for serving slice onions raw in a salad or sandwich: soak them in a little water with lemon juice or vinegar to remove the harsh bite of the onion!


Method for Slicing an Onion into Onion Rings


1 Cut off the stem end. Peel back the outer peel of the onion.

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2 With the peeled onion on its side, slice off a thin sliver from the side. Then place the onion on the cutting board with this thin sliver cut side down. This will stabilize the onion's position so as you slice the onion rings, the onion will not roll.


3 Curl your fingers inward as you grip the onion to protect your fingertips. Slice the onion in whatever thickness you desire.  If you wish separate the cut disks into separate onion rings.

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  1. doug kaiser

    What ya know…I finally find out HOW TO SLICE AN ONION ….. my daughter and I went to lunch and she ordered her Hamburger with grilled onion and so I took what was left over home with me. I ate my half of burger and then hers which she did not eat….she is pregnant……WOW grilled onion,,, what a flavor on a burger and I ate them cold out of the fridge. So I started to investigate grilling onion and how they are cut and ended up on your site…..THANK YOU SO MUCH for this eye opener. I am on Social Sec. and I eat onion sandwiches often…sometimes with cheese and some time all by them selves. Am going to practice slicing…so thanks for the tips.

    • Elise

      You’re very welcome Doug!

    • doug kaiser

      I noticed the knife you use is large…is that your standard knife you use as a chef or just for that cutting of the onion. It seems no matter how I cut an onion, I always mess it up. I have been buying chopped onion in a container and using it when I cook which is not often. I appreciate your quick answer and surprised….with a smile THANKS Elise.

      • Joy Morris

        That’s a standard size chef’s knife she’s using. I use the same sort of knife for most kitchen tasks. Victorinox (those clever people who make Swiss Army knives) has an excellent quality but very affordable chef’s knife. The first time I used this brand of knife it felt like the onions were cutting themselves!
        Knife skills are acquired by diligent practice and good tools. To quote my own grandmother “The only thing you’re sure to cut with a dull knife is yourself.”
        I am not affiliated with Victorinox in any way. This is my own opinion.

  2. Eliza

    My family swims, and we found out that your eyes don’t water if you wear sealed goggles while cutting onions… it’s been very helpful!

  3. Joy Morris

    I like to wear safety glasses over my regular glasses and turn on my ceiling fan while slicing onions. Not as good as swimming goggles but much safer for me as I need to have my glasses on to see what I’m cutting. :)
    Recently I happened across an old Julia Child tip for washing the onion smell off of hands and I think she was really on to something. After dealing with onions first wash your hands with COLD water and soap then repeat with hot water. Washing with hot water only seems to sort of cook the onion residue onto your skin. Well, my skin anyway.

  4. Tina

    The best way I was taught by a European friend of mine to get rid of onion smell on hands, was to wipe your hand with anything that is stainless steel. Some kitchen supply stores sell a stainless stone, but you can use your cutlery (spoon is safe). Seems to work well for me. Am about to try your recipe for French onion soup today. Read all the comments and am looking forward to it. I do not like onions in general, but soup is great. Plus being sick seems to make me crave it, as it seems other commenters have seemed to feel the same way, and said it made them feel better. Here’s to health the way God intended – from nature / natural.

  5. Byron Bales

    Wanna stop crying when you slice onions? Simple. Squeeze an orange skin over the bridge of your nose, close to your eyes. No orange? Just use a dip from orange juice and press it close to your eyes, near the bridge. No idea why it works, but it does.