How to Chop an Onion

Slicing onion
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Chopping an onion is one of the most common kitchen tasks, as well as one of the easiest — assuming you know the right way to do it.


Watch Now: The Best Way to Chop an Onion

  • 01 of 10

    First, the WRONG Way to Chop an Onion

    The WRONG way to chop an onion.

    The Spruce / Danilo Alfaro

    Many cooking instructors teach a technique that involves making horizontal cuts in the onion. But trust me, you don't want to do it this way — not ever! Even if your health insurance premiums are all up to date and you have a team of Red Cross volunteers standing by to give you a blood transfusion, don't do it!

    Why? It's simple: Cutting sideways through an onion toward your own fingers is just ridiculously dangerous. You WILL cut yourself. Badly.

    Seriously, don't do it.

    But even if you had titanium hands, there'd still be no reason to cut an onion this way. An onion's natural structure already has these horizontal cuts in it, so making more is just a waste of time. And then, when you consider that the inevitable result of using this technique is a trip to the emergency room — well, honestly — did I mention, "don't do it?"

    OK, enough said about that. Now let's find out the right way to chop an onion.

    (By the way, in step 5 I will reveal the cure to watery eyes from slicing onions.)

  • 02 of 10

    Trim the Ends Off the Onion

    How to Chop an Onion

    The Spruce / Danilo Alfaro

    Before you begin, make sure you have a cutting board and a sharp knife. You might also want to review this tutorial on How to Use a Chef's Knife so that you're familiar with the basic grips. And if you need a quick orientation on the different parts of a chef's knife, check out this article on The Anatomy of a Chef's Knife.

    Ready to get started? Place the onion on its side on the cutting board in front of you and slice off the top and bottom ends.

  • 03 of 10

    Cut the Onion in Half Lengthwise

    How to Chop an Onion

    The Spruce / Danilo Alfaro

    Your onion now has two flat ends. That's good because you can turn it so that it's resting on one of the flat ends and it won't roll around. You should have the other flat end facing up toward you.

    Now place the blade of your knife across the center of the upward-facing flat end. The edge of the blade should intersect with the little bulls-eye in the center of the onion. Carefully cut the onion in half by slicing straight down through the center.

    Note the way my thumb and forefinger form a sort of arch over the top of the knife. That lets me keep the onion nice and steady without getting my fingers in the way of the blade.

  • 04 of 10

    Position Your Onion

    How to Chop an Onion

    The Spruce / Danilo Alfaro

    We're going to work with one half of the onion at a time. Peel the skin off of one of the halves and position it so that it's resting flat on the board in front of you with the curved part facing up. The two flat ends should be pointing left and right.

    You're going to make your first cut parallel to one of those flat ends. If you're right-handed, you'll begin on the right-hand end of the onion, and lefties will start on the left.

    Continue to 5 of 10 below.
  • 05 of 10

    Slice Crosswise Through the Onion

    How to Chop an Onion

    The Spruce / Danilo Alfaro

    Are your eyes watering yet? People ask if there's a way to prevent your eyes from watering when you chop onions. And there is! One of my earliest kitchen jobs was at a French restaurant whose specialty was French onion soup. One of my tasks was to slice 50 pounds of onions every night. After about a month, my eyes didn't water anymore. So that's the remedy: Slice 50 pounds of onions every night for a month, and your eyes will become immune to onions.

    Anyway, the next step here is you're going to cut crosswise through the onion, slicing off little semi-circular sections as you work your way from right to left (or left to right for you lefties). Watch your fingers!

    The half onion is still positioned in front of you as before, round part facing upward, with the only difference being that it's been sliced into sections.

  • 06 of 10

    Flip the Sections Sideways

    How to Chop an Onion

    The Spruce / Danilo Alfaro

    Now you're going to flip a few of those sections sideways so that you end up with a little stack in front of you with the rounded part pointing toward your non-knife hand and their flat centers lined up and facing your knife-hand side.

    If this is all new to you, don't worry about stacking them. While you're getting the hang of it, just do a single section at a time. The stacks can be tricky because they can slide around a little bit.

  • 07 of 10

    Cut Downward Along the Straight Edge

    How to Chop an Onion

    The Spruce / Danilo Alfaro

    Unlike most three-dimensional foods, onions come with natural perforations in the form of those concentric circles that radiate out from the center. This technique uses the onion's natural structure to our advantage. If this were a corporation, we'd say we were "leveraging the onion's core competencies," but the truth is, we're just being smart.

    All we have to do is slice across the flat inside edge of the onion as if we were trimming little matchstick-shaped pieces. But because of the onion's natural perforations, those matchsticks will end up separating out into little cubes.

  • 08 of 10

    Slice Your Way Outward

    How to Chop an Onion

    The Spruce / Danilo Alfaro

    Keep trimming away toward the outer rings of the onion, letting those natural cubes fall onto the cutting board. And be careful when you get to the end because there's not much room for your fingers.

    Continue to 9 of 10 below.
  • 09 of 10

    Finish With a Quick Chop

    How to Chop an Onion

    The Spruce / Danilo Alfaro

    You'll see that those outer sections aren't going to form cubes all by themselves, so you'll have to help them along. Just give them a quick chop crossways to finish the job.

  • 10 of 10

    Perfectly Chopped Onion

    Perfectly Chopped Onion

    The Spruce / Danilo Alfaro

    As you can see, we've made quick work of that onion. Now just do one last inventory of your fingers to make sure you've got all the ones you started with, and you're done. That's all there is to it! Get cooking!

    Also see: How to Caramelize Onions