How to cut an onion

5 from 78 votes

Learn how to cut an onion properly with my easy knife tutorial. Diced or sliced, knowing how to cut onions will make food taste better and save you time.

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This is a guide for how to cut an onion. Below you’ll find a tutorial on how to slice and dice onions to use in soups, salads, sandwiches, stir-fry, stews and so much more. I’ll share tips on how to safely cut an onion, minimize waste and reduce any tears in the process – yup, it’s possible to cut an onion tear-free!

Cutting into onion

Across cultures, cuisines, and kitchens, recipes start with chopping an onion. Learn how to cut up an onion the right way and you will master a basic building block of cooking. Onions are high in vitamin C, loaded with fiber and have cancer-fighting properties. The average American will eat 20 pounds of onions in one year. I’m probably above average in this department haha! So let’s getting chopping!

 Onion cuts and uses:

  • Diced onions: This is the most common way to cut an onion. You can cut into large chunks or small pieces. The chopped onions become part of mirepoix, the onion-celery-carrot flavor bomb for so many soups and stews, or mix them raw in salsa or salad dressings. Their uses are endless.
  • Sliced onions: For thinly sliced onions or even thinly sliced half-moon onion rings, add them to your sandwiches, in stir fries or slow cook them into caramelized onions.
  • Wedge Onions: While not pictures below, this is another popular way of cutting an onion, which is essentially the beginning steps of slicing an onion. Tuck wedges into and around a roasting chicken for extra flavor or make them part of a sheet-pan dinner.
Sliced and chopped onions

Step by step tutorial

  • First, use a sharp knife. Really. A dull knife, quite literally, just won’t cut it. Instead of slicing cleaning through the onion, you will unsatisfactorily be tearing and gnawing through the vegetable.
  • Next, cut the onion in half alongside, not through, the root.
Large chef's knife cutting into onion on cutting board
  • Leaving the root  – that grassy- furry end – intact helps contain the enzymes that cause tears. Thank you, Chef Gordon Ramsay for sharing this tip with the world. By the way, other tear-prevention strategies include freezing the onion for 20 minutes prior to cutting or wearing swimming goggles.
Laying half the onion on cutting boards cut size down
  • Next, peel off the onion’s skin, still leaving that root intact.
  • Lay one half onion flat on your cutting board. Now you’re ready to dice, slice or cut wedges with the half onion. If you’re only using half an onion, you can store the half with the root intact in the fridge.
Collage showing how to peel an onion

How to cut onions: slicing

  • Point the knife towards the root of the onion, and allow your fingers to guide the slicing while your fingers are gripping the onion like a tennis ball. This is the safest way to chop an onion.
  • Slice vertically evenly as close to the root as you can. Space as your recipe dictates, either large wedges or thinner slices. 
  • Finally, cut off the root and discard it.
Sliced onions

How to cut onions: dicing

  • First, lay one half onion flat on your cutting board. Point the knife towards the root of the onion, and allow your fingers to guide the slicing. Slice vertically evenly as close to the root as you can. Again, make sure to grip the onion like a tennis ball, keeping the fingers pointed down.
  • Next, start dicing the onion by making horizontal cuts perpendicular to the ones you just made.
  • Finally, cut off the root and discard it.

And just like that, you have properly cut an onion! Keep practicing and you will get faster and faster.

Chopped onions on cutting board

How to store cut onions

  • Once peeled and/or cut, onions needs to be refrigerated.
  • Tightly wrapped onions with plastic wrap or in a silicone bag can be refrigerated for up to seven to 10 days.
  • If you want to chop ahead and freeze recipe portioned sized bags of chopped or sliced onions, make sure to remove all the air from the bag. They will be good for six to eight months.
Sliced onions on cutting board

Frequently asked questions

Should I refrigerate the bag of onions I buy at the store?

No! In a cool, dry, well-ventilated place, onions can last for up 30 days. They get mushy faster in the refrigerator, so don’t refrigerate onions before you cut them.

What size onion should I buy?

Recipes often call for either small, medium, or large onions. Keep in mind, a small onion is about the size of a lemon, a medium onion the size of a large apple, and a large onion the size of a softball. The National Onion Association – yes, there is one – says that a medium onion will come out to about a cup of chopped onion.

Sliced and chopped onions

Cutting an onion is one of those great skills to master in the kitchen because of the number of recipes that call for onions. If you can learn how to cut an onion, you can apply those knife skills to cutting many other fruits and vegetables. Get chopping!

Recipes with sliced onions

Recipes with diced onions

If you’ve found this cooking resource for How to Cut an Onion helpful or if you’ve tried any recipe on FeelGoodFoodie, then don’t forget to rate the recipe and leave me a comment below! I would love to hear about your experience with this technique. And if you snapped some shots of it, share it with me on Instagram so I can repost on my stories!

How to Cut an Onion

Learn how to cut an onion properly with my easy knife tutorial. Diced or sliced, knowing how to cut onions will make food taste better and save you time.
5 from 78 votes
Servings 1 serving
Course Tutorial
Calories 44
Prep Time 5 mins
Cook Time 0 mins
Total Time 5 mins

Ingredients
  

  • 1 large onion

Instructions

  • Using a very sharp chef’s knife, cut the onion in half cut in half vertically alongside the root.
  • Peel off the outer layers and discard. Leave the root end intact to make it easier.
  • To slice: Lay one onion half flat on your cutting board. Point the knife towards the root of the onion, and allow your fingers to guide the slicing. Slice vertically evenly as close to the root as you can. Cut off the root and discard.
  • To dice: Lay one onion half flat on your cutting board. Point the knife towards the root of the onion, and allow your fingers to guide the slicing. Slice vertically evenly as close to the root as you can. Next, start dicing the onion by making horizontal cuts perpendicular to the one you just made. Cut off the root and discard.

Notes

Storage: Store any chopped or sliced onions in an airtight container. They will last up to 5 days in the fridge.
Nutritional Data: The information below is an automated estimate for one onion only, which is not a recommended meal.
Photo Credit: Erin Jensen

Nutrition

Calories: 44kcal, Carbohydrates: 10g, Protein: 1g, Fat: 1g, Saturated Fat: 1g, Sodium: 4mg, Potassium: 161mg, Fiber: 2g, Sugar: 5g, Vitamin C: 8mg, Calcium: 25mg, Iron: 1mg

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Cutting into onion

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Comments

  1. Wonderful! Like learning how to play tic-tack-toe. Something so basic you feel you should have know this years ago. Thank you