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Learn how to cut an onion the easy way! This simple tutorial will leave you with perfectly sliced or diced onion in just a matter of minutes. 

Cutting onions on cutting board.
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Cutting Onions for Beginners

I’ll admit that cutting an onion used to take me quite a bit of time. I was always left with uneven pieces and would sometimes have to chop them a second time. But once I learned this easy method, that all changed. This really is the best way to cut an onion!

Chopped onions are in so many recipes. Whether you’re making a side dish, dip, soup, salad or main dish, there’s a good chance onions are included. They’re commonly used as an aromatic and give dishes that extra oomph in flavor.

When an onion is included on the ingredient list, that means there’s chopping involved. Which for some, seems like a chore. But not with this easy method! It literally takes 5 minutes and the onion is evenly sliced or diced every time.

There are many different varieties of onions, however the below are the most popular types to cook with.

  • Yellow: Great for roasting and making caramelized onions. They add amazing flavor to any dish.
  • White: A tad more mild than yellow, which means they can be served both raw or cooked. Add to fresh salsa or sandwiches or use in soups or when stir-frying or making roasted vegetables.
  • Red: A mild, sometimes spicy variety that tastes great both raw or cooked. Enjoy them raw in guacamole, salads or when making pickled onions. Or eat them cooked in fajita veggies.
  • Sweet: Such as Vidalia, are a sweeter flavor due to the higher sugar content. Also great for roasting and caramelizing.

Supplies Needed

  • Cutting board. Make sure it’s sturdy and has a large enough surface area.
  • Knife. A sharp Chef’s knife works best. The blade should be about 8 to 10 inches long.
  • Onion cutting goggles (optional). If you have a pair handy, definitely pull them out! If not, no biggie. You just might tear up a bit while you’re cutting onions. More on this below!

Why Do Onions Make You Cry?

Once sliced, onions release specific enzymes and sulfenic acid that can cause irritation in your eyes, which will most likely leave you in tears.

An easy way to combat this is to wear a trusty pair of onion goggles. You can also chill the onion in the freezer a few minutes before cutting, which helps reduce the amount of chemicals that are released.

How to Dice an Onion

Diced onion is great for adding flavor to main dishes, sauces, soups, stews and fresh dips like pico de gallo. I love this method because you’ll end up with similar sized pieces each time. Plus it’s super quick and takes just 5 minutes to perfectly peel and dice a whole onion.

Peel and slice in half. Start by cutting both ends off the onion. Then sit it up vertically on one of the flat ends that you cut. Slice the onion in half, right down the middle. Then remove the peel from both sides. Lay each half on the cutting board, center side down.

Cutting the ends of an onion.

Make vertical and horizontal cuts. Carefully place one hand at the top of the onion half and your knife at the bottom. Slice into the onion horizontally, but don’t cut all the way through. You want the knife to almost reach the other end, but stop before it does. Make about 3-5 of these horizontal slices.

Cutting an onion in half.

Then use the same technique to make vertical slices down the onion, stopping before you cut all the way through.

Dicing an onion with a knife.

Dice into pieces. Now it’s time to dice the onion. Start at one of the sides and use your knife to make vertical slices all the way to the other side. As you slice, it will dice into pieces. The width in between each slice will determine whether it’s a small to medium dice or large dice.

Dicing onions on cutting board.

How to Slice an Onion

Sliced onion is great for fajitas, salads or to make roasted veggies in the oven. This is my favorite way to slice an onion because the slices are long, thin and all similar in size, meaning they’ll cook evenly and quickly. Plus the slices look extra pretty when garnishing a dish!

Slicing onions.
  1. Start by cutting both ends off the onion. Then sit it up vertically on one of the flat ends that you cut.
  2. Slice the onion in half, right down the middle. Then remove the peel from both sides.
  3. Lay each half on the cutting board, center side down. Start at one of the sides and use your knife to make vertical slices all the way to the other side. The width in between each slice will determine how thick or thin they are. I prefer mine on the thinner side.

Slicing an Onion into Rings

Slicing red onions.
  • Cut both ends off the onion and then peel off the exterior skin.
  • Grip the onion with your fingertips (with the cut sides facing outwards) and then place your knife at the top of the onion on one of the sides. Carefully slice all the way down to the bottom of the onion, creating a ring-like shape. Make them as thin or as thick as you’d like.
  • Once cut, use your hands to separate the individual rings from one another. I like to start with the outer layers first. These work great as onion rings or to add on top of hamburgers or sandwiches.

How to Freeze Diced Onions

I don’t know about you, but whenever I go through the work of cutting an onion, I always make sure to dice extra so that I can freeze for later. It’s perfect for adding to soups and meats.

  • Add the cut onions to a freezer bag and seal the air out.
  • Write the date on the bag, or add a freezer label.
  • Store in the freezer for up to 3 to 6 months.
Freezing onions in a bag.

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slicing onions

How to Cut an Onion

5 from 1 vote
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Author: Jamielyn Nye
Learn how to cut an onion the easy way! This simple tutorial will leave you with perfectly sliced or diced onion in just a matter of minutes. 
Prep Time: 5 mins
Total Time: 5 mins

Equipment

  • Cutting Board
  • Sharp Knife

Ingredients 

  • 1 onion

Instructions

  • Cut both ends off the onion. Then sit it up vertically on one of the flat ends that you cut off.
  • Slice the onion in half, right down the middle. Then remove the peel and lay each half on the cutting board, center side down.
  • Dicing: Carefully place one hand at the top of the onion half and your knife at the bottom. Slice horizontally into the onion but don’t cut all the way through. You want the knife to almost reach the other end, but stop before it does. Make about 3-5 of these horizontal slices. Use the same technique to make vertical slices down the onion (stop before you cut all the way through). Then start at one of the sides and make vertical slices all the way to the other side. The onion will dice into pieces as you slice.
  • Slicing: Start at one of the sides and use your knife to make vertical slices all the way to the other side. The width in between each slice will determine how thick or thin they are. I prefer mine on the thinner side.

Notes

Yield: 1 medium onion will produce about 1 cup. 
To freeze: Add to a freezer bag and seal the air out. Then store in the freezer for about 3 to 6 months.
Course: Main Dish
Cuisine: American

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