How to Properly Cut an Onion

Have you ever stood at your cutting board in an attempt to dice an onion? Have you ever screwed up the process? I have. Years ago, I would cut both ends from the onion, somehow peel far too many layers of the onion away in an effort to remove the flaky skin, and then cut and cut and cut until I’d be left with nothing more than an absolute mess on my hands. While it’s not critical to slice, dice, or mince an onion so all pieces are consistently sized, it is preferable, especially if you’re browning the onions for further use. As I stood at my cutting board dicing, I wondered if there was a better way. Was there a technique I could use to dice an onion so the pieces didn’t scatter all over the place as I was doing so? Was there a method for holding the onion in its entirety as I was mincing? What did the professionals do? I couldn’t believe that I and a world-renowned chef were sharing the same terrible technique. That’s when I decided the learn the proper method for cutting an onion. After all, Gordon Ramsay regularly challenges Hell’s Kitchen contestants to complete tasks like this. Why shouldn’t I learn too?

Let’s start with first things first…

In This Post

How to Avoid Tears While Cutting an Onion

If you’ve been searching the internet for the best way to cut onions without crying, I’m sure you’ve stumbled across countless articles on the subject. And I’m also sure you’ve found some absolutely ridiculous suggestions. The one I love most is to cut an onion in the sink under running water. As if the pieces of onion weren’t going to wash off your cutting board into the drain. That was a good one. Here are some other methods that have zero chance of working:

Splash lemon juice on your knife before cutting the onion.
Light a candle nearby before cutting the onion.
Chew gum while slicing through the onion.
Wear goggles or big sunglasses (or glasses) while cutting.
Hold a piece of bread in your mouth while cutting the onion.
Microwave to heat the onion before cutting into it.
Hold your tongue to the roof of your mouth and breathe through your mouth while cutting.
Cut and discard the base (root) of the onion before cutting in earnest.

Obviously, some of these ideas are totally out there. Some do have a slight chance of helping the burning eyes issue, but aren’t great.

So what does work? Well, in order to answer that question, you’ll need to think about what’s actually going on. Two things: first, an irritating gas is being released from the onion, and second, the gas is making its way to your eyes while you stand there cutting. Simple enough. So the goal is to reduce the amount of sulfur gas that’s released and to stop the gas that does get released from making it to your eyes.

To make a long story short, in order to reduce the amount your eyes burn and tear while cutting onions, you’ll need to:

Freeze the Onion for 15 Minutes Before Cutting into It – doing this will effectively neutralize the gas so much less of it will have the ability to make your eyes burn.
Use a Fan to Move the Air in the Room in Which You’re Cutting – that’s right, in order to reduce the concentration and stop the gas that’s released from the onion from burning your eyes and making them tear, you’ll need to physically move the gas away from your eyes. An excellent method for doing this is to use a fan.

Sometimes, it takes a little bit of science and well as common sense to solve a problem.

PRO TIP: When cutting onions, use a very sharp knife. If you were to hold an onion in your hand and squeeze it so it sat in your palm like a pile of mush, you’d be releasing every last wisp of irritating enzyme into the air, which would instantly gas up the room. You’d be crying in no time. By using a sharp knife, you’re limiting the bruising of the onion cells and in effect reducing the amount of gas that’s released.

Why & How to Properly Peel an Onion

I’ll tell you right now, not all onions are built the same way. Some are very easy to peel and allow you to grab hold of and peel off the very thin outer layer. Others, however, are a real pain in the butt. It seems that half the onion needs to be peeled away, just to get that outer layer off. In both cases, there’s a better way. Learn it and get used to it. The goal is to neatly and efficiently peel the onion as to avoid waste. After all, most onions are sold by the pound. The thicker the peel, the more money you’re throwing away.

There are going to be instances when you don’t need to peel your onions. Let’s say you’re roasting onion halves or quarters in the oven. In cases like these, the skin of the onion can actually keep the interior from burning. Also, if you plan on making a broth and you’ll be straining away the vegetables afterwards, the exterior of the onion can actually alter the flavor of the broth in a positive way. Generally speaking, in all other cases, you’ll need to remove that annoying papery skin.

To peel an onion:

Cut the onion in half, from tip to root. The root is the fuzzy end or the one with what looks like course hair. The tip is the end that comes to a point.
Then, cut off the tip, but leave the root. The root is what keeps the onion intact for later use.
Finally, on the tip end, grab hold of the thin outer layer and pull it toward the root. When you get to the root, keep pulling until the skin becomes separated from the rest of the onion. The trick here is to remove as little of the onion as possible, while removing all of the papery layer as well as the thin layer directly beneath that.

How to Slice an Onion

Why would you want to slice an onion? I do when I’m caramelizing them. I also like to place raw onion slices on burgers as a topping. Slicing onions also comes in handy when you simply don’t need to dice or mince them. It’s less work to slice.

In the above photo, do you see how the root end is still on the onion? That’s keeping all the layers together. That comes in handy for whatever type of cut you need to make. In this case, it’s a simple slice, so the process is fairly straightforward.

To slice an onion:

Place the onion half face down, so the flat side is facing the cutting board.
Begin slicing across the onion, starting at the tip (cut) side.
Slice each piece your desired thickness all the way to the root end.
When you make it to the root end, stop and discard the root itself.

To hold the onion, make a claw with your holding hand and press the onion down firmly with that hand. Be sure to keep your fingers a good distance from the knife blade. Then, use the base end of the knife blade and push smoothly through the onion. The claw shape keep your fingertips out of the blade’s way, protecting them.

How to Dice an Onion

To dice an onion, you’ll be making three different directional cuts. First, you’ll slice straight down, or vertically, towards the root. Then, you’ll cut flat, or horizontally, towards the root. Finally, you’ll cut across, from side to side, from one end of the previous cuts to the other.

To dice an onion:

Start off by making vertical cuts towards the root.
Next, like you’d fillet a fish, slice horizontally toward the root.
Finally, make your cross-cuts, from one side to the other.
When making the first two cuts, be sure to stop before making it all the way to the root. Stay back maybe a half inch or so. The goal is to have the root keep all the onion’s layers together so the cutting is easier and the onion doesn’t fall apart.

When you cut about a half inch from the root, stop and discard the root.

How to Mince an Onion

Sometimes larger pieces of raw onion can be harsh. Even larger pieces of browned onion in sauces, such as tomato sauce, can seem awkward, so the question is, why should we mince onion? To cut down on the power of the onion itself. Minced, or smaller pieces of onion are perfect to add to burger meat, salads, meatloaf, as well as many types of sauces.

Minced onion is simply smaller pieces of diced onion. To get minced onion, the previously diced onion is chopped up until each piece of minced is about 1/10th the size of the diced. How do we get there?

To mince an onion:

Follow all the instructions above to dice an onion.
Pile the diced onion on a cutting board and rock your chef’s knife back and forth across all pieces until the onion is cut as fine as necessary. Be sure to hold the end of the knife in place and simply lift and push the handle of the knife up and down.

Mincing an Onion with Chef's Knife — Mincing an Onion with Chef’s Knife

Can you Store Cut Onions?

Absolutely. Once you cut your onion, place it in a bowl and tightly cover the bowl with plastic wrap. You can just as easily use an airtight container such as Tupperware. Onion will keep in the refrigerator for about a week.

One Last Tip

Sometimes, dicing onions using the method above simply doesn’t jive with who you are. What I mean is that, no matter how hard you try, making vertical cuts and then horizontal cuts and then cross cuts seems, well, contrived. Like, professional chefs try to out compete each other with how inefficiently they can cut an onion this way. Above, I’ve described the reasons one might want to take this route, but below, I’ll offer an alternative.

To use an alternate method for dicing an onion:

Cut the onion in half, lengthwise.
Cut both ends off the onion.
Peel the onion.
Slice each half of onion crosswise so you have half-moon slices (like in the slicing section above).
Turn the onion 90° and cut the same way as the previous step, but perpendicular to the previous slices. You should end up with a nice dice.

Dicing an onion this way is simple and fast. Sure, it might not stay together as effectively as the above method, but for amateurs like me, it works great.

Do you have any tips to add? How do you cut an onion? What’s your favorite method? I’m open to learning, so if you have something to share, please do in the comment section below. Thanks!