How to Cut an Onion Like a Real Chef

Kitchen Expert Clark Grant gives you his tips to reduce crying when cutting onions, and guides you step by step in the four most common ways to cut an onion.

A knife placed into an onion

All photos by Clark Grant

As a working chef, my wife is awesome and likes to cook for me most nights. I am super thankful for this, as I feed people all day long every day. The one item she makes me get off the couch to help her with, however, is onions. I don't know why. I don't argue with her. I just say, "Yes, honey,” take care of it quickly, and go back to whatever I was doing. Due to my career, I don't find cutting onions to be an intimidating task, but it is for many home cooks. Throughout this article, I will show you some tricks and techniques to make you more comfortable with cutting onions.

Reducing Crying While Cutting Onions

First, when most think of cutting onions, they think, "This is gonna hurt my eyes. I'm gonna cry tears of culinary despair." While this is true, I can tell you a few things that can help keep you from looking like you just watched the Red Wedding episode in Game of Thrones. As for the science behind why onions make you cry, they have a defense mechanism that helps to prevent animals from consuming them. When damaged or cut, onions release an enzyme that attacks the nearest water source, which in our case is our eyes. There is no foolproof way to stop this. However, the more you cut, the more your eyes grow accustomed to this enzyme, and the less you cry.

As for the tricks I promised, the best one I know is to refrigerate your onions. I do not know the scientific reason for this, but cold onions always make my eyes water less than room temperature ones. Also, you might look dumb, but you can wear swimmers' goggles as well, if you happen to be highly susceptible to crying when cutting onions. Listen, I have watched prep cooks wrap their entire faces in plastic wrap as makeshift onion goggles for cutting copious amounts of onions to be used in French onion soup. If it works, the people poking fun will be the ones crying, while you are there cooking bomb food with dry eyes! Contact lenses can also cause more irritation, so if you wear them, maybe switch to your glasses while cutting onions. Another surefire way to reduce crying is to ensure your knives are razor sharp. When you slice the onion with a sharp knife, you reduce the amount of the enzyme it emits, which in turn reduces eye irritation.

For this article, we will talk about four main ways to cut an onion, based on what I see in most recipes. They are as follows: rings, petals, diced, and sliced. In all of these cases, you will need to peel your onion first. But I will discuss the different methods for peeling based on the desired application, since each application has a different preferred method for peeling. Regardless of application, I highly recommend you slice your onions just before you are ready to use them to reduce oxidation, which causes sharp, acrid flavors to develop in your onion. Don't believe me? Slice an onion and store it in your fridge overnight. The next day, slice another one the same way. Smell and taste the difference between fresh and day old, and you will be converted to always slicing right when you need it. For all of the following methods, place your onions in the refrigerator for a couple of hours ahead of time, and you can thank me later.

Onion Rings

Step by step guide to cutting onion rings. Slicing the ends off, peeling, cutting into rings, separating rings and removing membranes.

Onion rings are quite possibly the most wonderful fried delight for an onion lover. Beautiful, lacy, light beer batter on a Vidalia is a heavenly side dish to a well-prepared burger. (Note: I am from Georgia, and to me, there really is no onion that compares. Also, pronounce it like you're a native by calling it a vy-dae-ya onion. Don’t church it up by calling it a vi-dall-ia, we aren't that fancy down south!) For onion rings, we are hoping to get full layers of onion in ring form. You can use this method for fried onion rings, for slices to put on a burger, or for really any other application where you would want to keep the rings of the onion attached. Take your onion and slice off the end that is opposite to the root end. Using a sharp paring knife, do your absolute best to slice through just the outer layer of the onion, so you can easily peel the onion skin and first layer off of the onion — only to be left with the more usable parts in the center of the onion.

After you have done that, place your onion on a towel to keep it from rolling around on you, so you can slice it safely. Slice your rings into your desired thickness, based on your application. Continue to slice your onion until about a fourth of an inch from the root end. If you are using it on a sandwich or burger, you are done. If you are wanting to make onion rings, we will go a few steps further. For onion rings, separate the individual rings and soak them in ice water for 15 minutes. If you have ever eaten an onion ring only for all of the onion to slide out of the batter on your first bite, we are going to fix that issue next. After your onion has soaked, remove them from the ice bath, and dry them on a clean paper towel on your cutting board. Next, peel the membrane from the inside of each ring. This is tedious, but you want the best, right? Now, proceed with your favorite beer batter, bread crumb breading, or tempura batter, and enjoy perfectly crisp, sweet, flavorful onion rings.

Onion Petals

This method is my favorite for adding to a salad or for sautéing. We are going to dig a bit into the cell structure of onions to explain why I prefer cutting onions with this method for certain applications. If you look at an onion slice, you will notice that slicing parallel to the hemisphere of the onion results in onions that are easy to break apart and crumble. For petals, we are going to slice against the hemisphere, cutting with the cell structure to produce a product that does not break apart as easily. Think of this like you think of cutting a steak. If you cut with the grain, you will have a more tough bite of steak. If you cut against the grain, you will have a more tender cut of meat. Onions can be thought of in a similar way.

For French onion soup, I want my onions to hold their shape and character so that I can showcase them after intense cooking. So we are going to cut them "with the grain," if you will. To cut this way, cut off both ends of your onion, and cut in half from end to end. Place your cut onion, flat part down, on your cutting board. You are going to work your way from side to side on each of your onion halves, cutting what look like flower petals. You will need to angle your knife a bit on each end to get a full yield from your onion. Use your knuckles to guide the knife blade so that you end up with uniform petals and you keep your fingertips out of the way of the knife blade. You can apply onions that are cut this way to stir-fries, onion soup, fajitas, salads, etc. To me, this is the most universally usable way to cut an onion, and often my go-to.

Cutting onion petals and slicing onions

Sliced Onion

Sometimes you want onions to disappear a bit as you cook them. Maybe you are making a stew and you want onion flavor, but want to reduce the visibility of the onion in the finished product. You can finely dice your onions, or you can just slice them the opposite of how we made petals when looking at the halved onion. You are cutting "against the grain" with this application. The cell structure will allow this onion to kind of melt into the dish and almost disappear. You can cut half-moons this way, or go even further and cut each onion half in half again to create quarter-moons. This is my least used method for cutting onions, but I will use it if I am making a sauce that I am going to blend in the end anyway, as it is one of the quickest and easiest ways to slice an onion.

Diced Onion

How to dice an onion. Cut through root, peel, make horizontal slices, make vertical slices, final hemispherical cuts, diced onion.

Here is where we get into the real sorcery with onions. To create a uniform dice, please start with a sharp chef's knife. If you are having to work to cut your onion, it is time to sharpen your knives. Don't just start hacking away to create chopped onions. Remember that enzyme I talked about and also the acrid, sharp onion flavor we want to avoid? Sharp utensils and cutting properly will keep those two things at bay better than anything else. To start, cut the top end (non–⁠root end) of the onion off. Then, cut the onion in half, perpendicular to its hemisphere, so that you have two cut sides of the onion, each with a flat surface and the stem end still attached. Now, grip the onion with a towel and very carefully slice it parallel to the cutting board until you reach about a fourth of an inch from the root. If you want large chunks or large dice, then you may only make two to three slices in this manner. If you want finely diced or small pieces (such as for salsa), then you will want to make seven to eight slices this way. You have to make this decision based on what your recipe calls for.

After you have completed this, you are now going to slice through the onion with the tip of your knife facing the root end. Okay, so now you have these two halved onions that are still "intact,” but with slices running from the poles and parallel to your cutting surface. Now for the satisfying, easy part. Cut your onion from the non–⁠root end straight across. As you cut, you will notice that perfectly uniform diced onion will be left on your cutting board. Easy as that. That is how professional cooks do it, and so can you. It might take you a little practice, but don't be afraid of it — just respect your knives and be careful. You can do it. I believe in you, and I haven't even met you!

Get Cooking!

Take these methods and attack some onions. Make the onions cry—don't let them make you cry. You know onions can smell fear, right? Not really, but you are now equipped with some knowledge to increase your skill level when handling all types of alliums (yellow onions, sweet onions, red onions, leeks, shallots, etc.). If you need some help with picking out a new knife or cutting board, you can speak with one of our Cutlery Experts here on Curated. Remember, no one is going to make fun of your onion goggles once they taste your food!

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Written By
I grew up cooking with my grandmother and great aunt learning to bake first and then falling in love with food in general. My culinary career has taken me from Georgia to Chicago to now Kansas City. I have helmed the kitchen in top Steakhouses in Chicago and Kansas City as well as fine dining Italia...

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