How To Slice An Onion

A plate of whole shallot onions next to a stainless steel kitchen knife

How To Slice An Onion

  1. Cut off the stem end with a sharp knife.
  2. Cut the onion in half through the root end.
  3. Remove the papery skin.
  4. Place onion with the flat side facing down. Hold firmly.
  5. Slice the onion from one stem to the other.
  6. Repeat with the other onion half. 

Sharp kitchen knife on a wooden cutting board next to chopped green onions

Gladiator Series Kitchen Knives | Dalstrong ©

    This Is What You’ll Learn

    1. A Few Things About Slicing Onions
    2. What’s The Difference Between Slicing, Mincing, Chopping And Dicing?
    3. How To Slice An Onion
    4. How To Cut An Onion Into Rings
    5. How To Dice An Onion
    6. How To Brunoise An Onion
    7. How To Cut An Onion Julienne
    8. How To Quarter An Onion
    9. How To Cut An Onion Without Crying
    10. Frequently Asked Questions About Slicing Onions
    11. Best Knives To Slice An Onion With

      If you’re a home cook, then you already noticed onions are present in almost every savory recipe. Sauces, burgers, salads, meat or chicken. And even if you have your apron on and are feeling international: almost every cuisine in the world takes advantage of this noble vegetable.

      This is why learning how to cut or chop an onion is an essential knife skill to master. There are several ways to slice an onion, resulting in different sizes / shapes that are good for certain recipes. In this article we’ll walk you through all of them!

      1. A Few Things About Slicing Onions

      A silver paring knife with a hollow stainless steel handle next to thee onions and cloves of garlic

      Crusader Series Kitchen Knives | Dalstrong ©

      1. If you’re slicing onions for a salad, for example, you can go with your intuition and get away with it. But for other more elaborate recipes, slicing an onion the right way is important because the shape, size and consistency really make a difference.
      2. Take a minute to familiarize yourself with the anatomy of an onion. Every onion has a root end and a stem end. You can leave the root in most cases to help the layers hold together while slicing, just make sure it’s clean. Also, follow mother nature: after you peel your onion, you will see lines across the “globe”, follow these lines as a guide.
      3. Picking a good onion will result in better slices. Choose dry, heavy, firm onions and avoid any onion that looks brownish or feels too soft.
      4. Historically, chef’s knives are the best tool to cut an onion; but when peeling off the onion, you can get help from a paring knife. Also, if the next layer below the skin is looking a little funny (soft or wrinkly), remove it as well. 
      5. To protect your fingers, curl them inward as you grip the onion.
      6. We recommend using a rocking motion movement with your knife, keeping the tip down. 
      7. When serving raw onion slices over a salad or a sandwich, you can soak them in cold water with lemon juice or vinegar for around ten minutes to get rid of the strong flavor.

      2. What’s The Difference Between Slicing, Mincing, Chopping And Dicing?

      Sliced white onions covering a portion of a Japanese kitchen knife on a wooden cutting board

      Phantom Series Kitchen Knives | Dalstrong ©

      When explaining how to prepare an onion, recipes might use different words like slicing, mincing, chopping, dicing, lengthwise, crosswise… and the difference is not unimportant. How you cut an onion affects the cooking process, the cooking time, the appearance and in some cases even the taste. 

      • ‘Slicing’ means cutting something into thin pieces using a quick, fluent movement. Onions can be sliced lengthwise (from root to stem. Lengthwise slices hold their shape more firmly) or crosswise (pieces will fall apart easily, for example as raw onion slices on a salad).
      • To ‘chop’ onions usually refers to cutting into chunks without requiring a specific size or shape.
      • A ‘minced’ onion is an onion that’s been finely chopped.
      • ‘Dicing’ is to cut something into small cubes or squares. In this case, the shape is important, but the size may vary. 

      3. How To Slice An Onion 

      Close up of red onions chopped in half against a black background next to a stylish kitchen knife

      Omega Series Kitchen Knives | Dalstrong ©

      With this method you’ll obtain onion slices, also known as onion strips, half moons or half rings. 

      This is the cut you need for caramelized onions, fresh onion soup, fajitas, etc.

      1. Cut off the stem end using a sharp knife.
      2. Cut the onion in two halves through the root end (meaning: lengthwise).
      3. Remove all the outer papery skin (and the next layer of skin too, if necessary).
      1. Place the onion with the flat side facing down. Hold firmly by the root end. 
      2. Slice onion to your desired thickness from one stem to the other.
      3. Separate layers with your hands if necessary.
      4. Repeat with the other half. 

      Take into account that the strips might not be the same size when you’re using this technique. The difference might be small or significant, since the pieces coming from the center of the onions will be smaller than the outer layer. 

      4. How To Cut An Onion Into Rings

      onion cut into rings on cutting board

      This is the technique you need to master to make some delicious homemade onion rings, or to put on top of a burger (in this case, cut thicker) or a salad (in this case, cut thinner).

      1. Remove both the ends
      2. Peel off the onion paper (paring knives are great here)
      3. Pick one side and cut a small piece to create a flat side that serves as a stable base.
      4. With the flat side facing your cutting board, position your knife the same way you did to cut off the ends. 
      5. Begin to create slices carefully to the appropriate thickness depending on the recipe.
      6. When the whole onion is sliced up, separate the rings with your hands.

      5. How To Dice An Onion (Chop Into Cubes)

      diced onions on counter

      Best for onion soups, onion-based sauces, chili, pico de gallo or chicken stock.

      When a recipe asks for a “diced onion”, it means you should chop it into squares or cubes. Here, it is important that the cubes are neat and uniform, so they fry evenly. There are several methods to dice an onion, this is by far the easiest one:

      1. Cut the onion in half. This time, do not remove the roots, as they will hold the onion together.
      2. Take one half (the root should be opposite to the knife) and make vertical cuts (towards the root, but without touching it). Try to leave even spaces between the cuts.
      3. Now make horizontal cuts, holding the onion firmly against the board. Voila! This will create small cubes because of the onion’s natural layers.
      4. Repeat on the other half. 

      6. How To Brunoise An Onion (Tiny Cubes)

      diced onions into cube on cutting board

      “Brunoise” means very small dice. This cut works best for sauces or soups; as well as dishes topped with onion sprinkle as garnish. 

      1. Cut in half through the root (top to bottom), but leave the root intact for most of the cutting process. 
      2. Peel the outer skin.
      3. Place onion so that the flat side is on your cutting surface and the root is facing away from you.
      4. Slice through the onion following its natural lines (but don’t cut through the root).
      5. Turn the onion 90 degrees and slice parallel to the table or cutting board.
      6. Finally, slice horizontally to chop the dice entirely. 

      7. How To Cut An Onion Julienne (Thin Slices)

      Julienne cut onion

      Julienne is just the fancy name for thin strips of onions. The advantage of julienne cuts compared to regular slices / strips is that the resulting onion pieces are fairly consistent in size and shape, which is essential for certain recipes. 

      Best for: Scattering onion over focaccia or pickling, sautéing, stir-frying, and caramelizing onions.

      Beware, julienne is the only cut where you’ll cut off the root end at the beginning.

      1. Begin the process just like when you’re cutting half-moons, except this time, remove the root end.
      2. Cut off the stem end and peel the onion.
      3. Cut in half (you’ll be working with one side at a time)
      4. Start slicing the onion lengthwise at an angle. You need to make radial cuts, slightly changing the angle every time. Because of the onion’s round shape; this will create finer and more consistent slices.

      8. How To Quarter An Onion

      cut quartered onion

      Some recipes may require a quartered onion, like roast beef, baked chicken or stews.

      1. Cut the stem off
      2. Remove papery skin
      3. Halve the onion down the middle
      4. Cut the onion in half the other way (vertically, cutting each half into two pieces)
      5. You will now have 4 pieces

      9. How To Cut An Onion Without Crying

        Onion cells contain chemicals called sulfoxides, which turn into fumes when an onion is cut, and are released into the air. These fumes then have a chemical reaction with your eyes, creating a burning sensation and resulting in… tears.

        So yes, this is a natural, chemical process and I can accept that… but I don’t want to be crying during my otherwise liberating experience of cooking my favorite recipe. More than that; the burning feeling is actually annoying, even painful.

        So how can we avoid crying when cutting an onion? 

        • Use a sharp knife. If you use a high-quality, properly sharpened knife; the damage to the onion skin will be less; and therefore, less acid is released into your eyes. So make sure you’re using the right knife (more on that later) and that it’s sharp and ready.
        • Keep the cut side of the onion facing down to your cutting board, at all times.
        • Freeze the onion. Some people remove the skin and put the onion in the freezer half an hour before slicing; and reportedly, it works!
        • Limit your exposure to the pieces of onion you just cut. If you cut the onion in half; “hide” the intact half away (with skin) while you cut the other. And after cutting, quickly put the chopped onion away to a bowl and wipe your cutting board.
        • Soak onion in cold water: this hasn’t been proven, but apparently, soaking the onion in cold water would neutralize some of the cruel chemicals.
        • Wear goggles or a face mask (like those used during the pandemic). Not the most glamorous option on the list, though… 
        • Cut near a fan or a kitchen vent. This will help the fumes circulate and not accumulate around your face.
        • Fast, proper cuts. Try to move quickly (but safely) with your knife following the steps above. This will limit the time you spend being exposed to the fumes.

        10. Frequently Asked Questions About Onions

        A black nakiri knife surrounded by chopped vegetables

        Shadow Black Series Kitchen Knives | Dalstrong ©

        How can I store a sliced onion?

        Use an airtight container or a zipper bag. Store in the refrigerator for up to 10 days or in the freezer for up to three months (note, the longer you wait the harsher the flavor).

        What is the best type of onion for cooking?

        Usually, yellow onions are every chef’s favorite. When a yellow onion cooks, it becomes sweet and tasty, while holding up tightly. However, white onions are totally acceptable and ideal for raw preparations. Red onions are slightly spicier and great for salads.

        What's the difference between a shallot and an onion?

        Besides having a different shape; shallots and onions have different flavors. Onions tend to be more intense; while shallots have a more delicate taste. 

        What kind of onions should I slice for onion rings?

        White onions or yellow onions work best for onion rings. Some people like to use sweet onions, like for example the Vidalia onion.

        How can I peel a pearl onion?

        Peeling a pearl onion can be challenging. Put the onions in boiling water for two minutes, and then let them cool. Squeeze with your hands, and the skin should come right off.

        11. Best Knives To Slice An Onion With

          1. Chef's Knife 10" | Delta Wolf Series

          Chef's Knife 10" | Delta Wolf Series | Dalstrong ©

          Definitely non-traditional, not only for its 10" length but also for its bold design. This versatile knife brings strength, agility and durability to undertake a variety of culinary adventures: from cutting onions without crying; to chop, mince and slice any vegetable, meat or fish.

          PROS:

          • The onyx-black, high-carbon steel blade is superbly elegant and original.
          • The titanium nitride coating enhances strength, corrosion protection and non-stick properties.
          • Thanks to the structure and tapered design, this knife has the necessary agility to cut onions quickly or anything else you want.

          CONS:

          • The design might come as too extravagant for some.
          • You may also prefer a classic 8" chef's knife.
          • Not the most expensive item on this list; but still on the pricey side.

          2. Chef & Cleaver Hybrid Knife 8" | Crixus | Quantum 1 Series

          Chef & Cleaver Hybrid Knife 8" | Crixus | Quantum 1 Series | Dalstrong

          This innovative knife combines the legendary versatility of a chef's knife with the sharpness of a sword. You can cut onions into julienne, rings or brunoise; easily and effortlessly.

          PROS:

          • Its blade is forged from ultra-premium steel made in the USA.
          • Flexibility, durability and hardness thanks to the addition of nitrogen.
          • The cutting-edge, geometric design reduces drag and improves grip for cleaner and faster cuts.
          • The modern handle is waterproof and promises total control.

          CONS:

          • The price may go beyond many home cooks’ budgets.
          • It is quite new in the market. This means that, even if it’s backed by Daltrong’s history of quality and performance; you still need to have an adventurous heart to try it out. 

          3. Serrated Sandwich, Deli & Utility Knife 6" | Gladiator Series

          Serrated Sandwich, Deli & Utility Knife 6" | Gladiator Series

          It’s almost impossible to find this kind of versatility at this price. This is an ideal multi-purpose tool for slicing onions and tomatoes, bread, cold cuts and deli meats. A true warrior in the kitchen, capable of multi-tasking and making it easy for you to be a chef.

          PROS:

          • Loyal, durable knife, precision-forged from a single piece of high-carbon German steel.
          • The serrated edge easily cuts through all types of fruits and vegetables, even those with a special skin such as onions.
          • The rounded tip is also good for spreading sauces (so this is a very helpful knife if you’re preparing any type of sandwich with onion rings!)
          • Unbeatable value for money.

          CONS:

          • Many would prefer the elegance of a premium chef's knife.
          • It is shorter in length, which can be uncomfortable for some cuts.

          4. Utility Knife 5" | Phantom Series

          Utility Knife 5" | Phantom Series | Dalstrong ©

          Cutting onions has never been easier than with this 5" utility knife from Dalstrong's Phantom series. Slices, dice or rings are cut quickly with a perfect finish, thanks to the scalpel edge of this knife that perfectly doubles as a chef's knife and a paring knife. 

          PROS:

          • The blade's design allows for scooping and transferring onions to a bowl after chopping. And of course, it also works with tomatoes and all kinds of herbs.
          • Forged from premium Japanese AUS-8 steel.
          • Easy to handle and control thanks to the Japanese D-shaped handle style, which fits perfectly in the palm of the hand.
          • Discreet and refined.

          CONS:

          • The beautiful, detailed Japanese engraving on the blade requires extra cleaning precautions.
          • For a utility knife, it may feel a bit lightweight. Some people prefer a heavy knife in this case.

          5. Paring Knife 4" | Omega Series

          Paring Knife 4" | Omega Series

          Agile, efficient, multipurpose paring knife from Dalstrong's Omega series. You can cut, slice and peel fruits, vegetables, herbs and even create detailed patterns on food. Especially comfortable for peeling your onion and working with shallots. 

          PROS:

          • The compact size of a paring knife is ideal for cutting, peeling, mincing and dicing (onions or anything else)
          • Combined with a chef’s knife for the actual cuts, it’s the perfect onion-prep team. 
          • Manufactured by experts and designed to last a lifetime.
          • The blade is engraved with a 'LiquidMetal' pattern that reduces drag.

          CONS:

          • It’s a bit heavier than the standard paring knife.
          • It might not be the most comfortable tool for larger onions. 

          Check Out Top Quality Kitchen Knives Today

          Written by Eva Contreras
          Food & travel writer based in Buenos Aires. Superpowers include relentless curiosity and high tolerance to spicy foods.