The 4 Most Useful Ways To Cut An Onion

Cutting onions is a crucial skill in professional kitchens and at home. With such a versatile ingredient, it’s helpful to know a variety of cuts and the best uses for each one.

After 15 years in the restaurant industry, I’ve cut my fair share of onions. In this article, I’ll share tried and true methods that I can pass on to you. 

To get you started, I’ll go over four of the most useful cuts: rounds, cubes, julienne, and quarters. Mastering these basics will serve you well and should get you through just about any recipe.

First, Trim The Ends And Peel 

person peeling onions by hand

Whenever I need to cut onions, I start by cutting off the root and stem, then peel the onion. No matter what type of cut you’ll be doing next, this should be your first step.

Firmly hold the onion against the flat surface of your cutting board and cut off the root end. You don’t need to remove very much. About a quarter-inch from the root will do. Then, rotate and do the same to remove the top.

This creates two flat bases that make the onion easier to cut and peel.

To peel, use your knife to make an incision through the outer layer of the onion. This gives you an easy place to start and makes peeling much faster. At this point, you can use your fingers or the heel of your knife to get the job done.

Pro-tip: A sharp knife is key for cutting onions. A sharp knife reduces the likelihood of injury and the amount of tear-causing enzymes that onions release.

The 4 Most Useful Cuts For An Onion

Sliced Rounds

onion rings

Thinly sliced rounds are great for salads, sandwiches, and garnishes. While thicker cuts are perfect for grilling or onion rings. 

  1. First, lay your trimmed and peeled onion horizontally on your cutting board. Orient the onion so that the cut-off root and stem bases are parallel with your knife.
  1. Hold the onion firmly and start slicing from one end to the other. Use the hand holding the onion as a guide to help make your slices more consistent.  

Diced Cubes

onion diced

Diced onion cubes are a cornerstone ingredient for soups, sauces, and salsa.

  1. Start by standing your peeled onion on one of its cut ends and splitting it in half with your knife.
  1. Then, place an onion half cut side down on your cutting board with the top and root ends facing left and right.
  1. Make your non-knife hand completely flat and press down on the onion. Now, very carefully make horizontal cuts starting at the top end and going towards the root end of the onion.
cutting onion in half
cutting onion half

Your knife will be parallel with the cutting board and the hand holding the onion.

You want these horizontal cuts to get close to the base of the onion without going all the way through. Make three to four of these cuts depending on the size of the onion. 

  1. Now, make several vertical cuts into the onion. Again, be sure not to cut through the root end that’s still intact. This will keep the onion together and make the next step much easier. Vary the thickness of your cuts depending on how big you want your diced cubes to be.
  1. Finally, make cross cuts perpendicular to the cuts you just made. Once you get to the root end, lay it flat and continue to cut it into small pieces. Or, save it for your next batch of stock.
onion cutting small cubes

Julienne

Julienne cuts are great for fajitas, stir-fries, french onion soup, and sandwiches.

  1. Stand a peeled onion on one of its cut ends and split it in half from top to bottom.
  1. Place an onion half on its flat side against the cutting board.
  1. Orient the onion so that the cut-off stem or root side faces you.
  1. Starting at one side of the onion, hold it in place and use your hand as a guide to make cuts at roughly 1/4in intervals. Feel free to make these cuts as thick or thin as you’d like depending on what you’ll be using them for.
cutting onions half
onion julienne

Pro Tip: As you make your julienne cuts, slightly slant your knife so that it’s always angled towards the center of the onion. This will give you the most uniform julienne without too many wide, flat pieces.

Quarters

These are big, chunky cuts that work great roasted, grilled, or in a stock or braise.

  1. Stand a peeled onion on one of its cut ends and cut it in half from top to bottom.
  1. Then, place the onion halves cut side down on your cutting board.
  1. Now, cut the onion halves in half again, going through the top and root ends of the onion. 
cutitng onion in half
onion quarters

How To Store Onions

Whole onions can last several weeks at room temperature in the pantry. Keeping them out of sunlight and heat will extend their shelf life and keep them from sprouting.

Cut onions can last up to a week in a sealed container or zipper bag in the fridge.

For longer-term storage, cut onions will last a couple of months in the freezer, but it will change their texture. So, I would only recommend this if you intend to use the onions for a soup, sauce, or stock. 

Frequently Asked Questions

How do you cut onions without crying?

Chill the onions before cutting and use a very sharp knife. Both of these things will help reduce the release of enzymes that irritate the eyes. And there is no shame in wearing safety goggles if you’re particularly sensitive.      

What’s the best way to cut an onion in half?

Firmly hold an onion on a cutting board and cut off both ends. With two flat sides, you can easily stand the onion up and cut it down the middle. 

How long will onions store in a container?

Cut onions will last in the refrigerator for about 7 days. While whole peeled onions can last up to 2 weeks. For even longer storage, consider freezing them. Freezing is great if you intend to use the onions for soups, sauces, and stocks. 

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person curling finger when cutting onions

How To Cut Onions With A Knife


  • Author: Ryan Limbag
  • Total Time: 5 minutes
  • Yield: Varies

Description

Learn how to cut onions with a knife into rounds, cubes, julienne, or quarters.


Ingredients

  • Onions

Instructions

Cut Off Ends And Peel

  1. Firmly hold the onion on a cutting board. Cut off one end about a quarter-inch in from the stem or root.
  2. Rotate and cut the opposite end off.
    person cutting the tip of onion
  3. Peel off the outer layer of the onion.
    person peeling onions by hand

Onion Rounds

  1. Place an onion on a cutting board so that the cut-off root and stem bases are parallel to your knife.
  2. Slice from one end to the other, creating rings as thick or thin as you’d like. 

Diced Cubes

  1. Cut the onion in half.
    person curling finger when cutting onions
  2. Place an onion half cut side down on your cutting board.
  3. Carefully make 3-4 horizontal cuts into the onion. Cut towards the root end without going all the way through.
    cutting onion on a wooden cutting board
  4. Make vertical cuts into the onion with your knife pointing towards the root end of the onion. Again, don’t cut through the root end.
    onion halves
  5. Make cross cuts that are perpendicular to the cuts you just made.
    cutting onions on awooden cutting board

Julienne

  1. Cut the onion in half.
    person curling finger when cutting onions
  2. Place an onion half on its flat side against the cutting board.
  3. Orient the onion so that the cut-off stem or root side faces you.
  4. Starting at one side, make cuts at roughly 1/4in intervals. These can be made thicker or thinner depending on the use.
    onion rings

Quarters

  1. Cut the onion in half.
    cutitng onion in half
  2. Place an onion half on its flat side on the cutting board.
  3. Split each onion half in half again, cutting through the top and root end of the onion.
    onion cut in a bowl
  • Prep Time: 5 minutes
  • Category: Knife Skills
  • Cuisine: Any

Keywords: how to cut onions, how to dice onions, how to julienne onions, sliced round onions, onions for salad, onions for soup, diced onions

About the author

Ryan worked the Twin Cities circuit as a line cook, sous chef, and kitchen manager for over 15 years. Though he doesn’t cook professionally anymore, he loves to share his restaurant expertise with anyone that needs a tip. Once a cook, always a cook.