Onions are a foundational ingredient in countless dishes. Whether you’re starting a hearty chili, simmering a flavorful chicken stock, or preparing classic French onion soup, knowing how to properly dice an onion is a fundamental skill for any cook. In fact, onions are estimated to be used in 30 to 40% of savory recipes, making them one of the first vegetables you should learn to cut when developing your knife skills. For many, including myself, the simple act of dicing an onion with a sharp knife is a satisfying and essential part of cooking.
:max_bytes(150000):strip_icc()/20220511-CuttingOnions-AmandaSuarez-_361-e0fb46e9615943d5b6c58c386a0ff958.JPG)
Serious Eats / Amanda Suarez
This guide will walk you through two primary methods for dicing onions: the traditional technique and a safer alternative. We’ll also discuss the nuances of different dice sizes and how they impact your cooking.
How to Dice Onions: The Traditional Method
The traditional dicing method is a cornerstone of culinary technique, efficient once mastered, and allows for precise control over the size of your dice.
:max_bytes(150000):strip_icc()/20220511-CuttingOnions-AmandaSuarez-_22-4aaf7ce251654c6abf47a2f5f695ceab.JPG)
Serious Eats / Amanda Suarez
The size of your diced onion matters depending on the dish. Large dice, around three-quarters of an inch or larger, are ideal for flavoring stocks and broths, where they will be simmered and later removed. These larger pieces release their flavor slowly and are also suitable for grilling on skewers or for dishes where they will be further processed after cooking. Medium dice, approximately half an inch, are versatile for hearty applications like stews, soups, braises, and robust sauces. Small dice, about a quarter inch, are preferred for smoother, more refined sauces, curries, and dishes like meatballs, meatloaf, salsas, and salads. When cooked for extended periods, small dice will almost completely dissolve into sauces, adding depth and texture.
Dice sizes smaller than small dice are known as brunoise. These extremely fine dice are less common in home cooking and are more often seen in professional kitchens for dishes requiring a very delicate texture, such as beef tartare or pâtés.
Step 1: Trim the Stem End
:max_bytes(150000):strip_icc()/20220511-CuttingOnions-AmandaSuarez-_3-7ea2c961e1214aa7aeef26a19c8a174e.JPG)
Serious Eats / Amanda Suarez
Begin by placing the onion firmly on your cutting board. Using a sharp chef’s knife, trim off the stem end, removing about half an inch. This creates a flat, stable base for safer cutting.
Step 2: Halve the Onion
:max_bytes(150000):strip_icc()/20220511-CuttingOnions-AmandaSuarez-_7-a2c8821753f24f40917350e69c8319d0.JPG)
Serious Eats / Amanda Suarez
Lay the onion on the flat surface you just created (stem end down). Carefully slice the onion in half lengthwise, cutting through the root end. Keep your non-knife hand firmly on top of the onion to stabilize it while slicing.
Step 3: Peel Off the Outer Layers
:max_bytes(150000):strip_icc()/20220511-CuttingOnions-AmandaSuarez-_9-45130528767b4214860635b7f17b8bdd.JPG)
Serious Eats / Amanda Suarez
Peel off the papery outer skin from each onion half. Often, the first pale layer of the onion directly beneath the skin can be dry and slightly tough. It’s recommended to remove this layer as well to ensure you are working with the tender, flavorful flesh underneath.
Step 4: Make Horizontal (Z-Axis) Cuts
:max_bytes(150000):strip_icc()/20220511-CuttingOnions-AmandaSuarez-_12-5482c51601db4107ad261bdbd7582c52.JPG)
Serious Eats / Amanda Suarez
Place the flat, cut side of the onion half down on the cutting board. Make a series of horizontal slices, running parallel to the cutting board (along the Z-axis). Maintain even spacing between your slices, depending on the desired dice size. Slice almost all the way through to the root end, but leave the root intact. This root end acts as an anchor, holding the onion layers together during the next steps. Position the onion close to the edge of your cutting board to provide ample clearance for your knife hand. The order of horizontal and vertical cuts (steps 4 and 5) is a matter of personal preference; choose whichever feels more comfortable for you.
Step 5: Make Vertical (Y-Axis) Cuts
:max_bytes(150000):strip_icc()/20220511-CuttingOnions-AmandaSuarez-_14-d2b7205b528b4152a5df91d05c25d396.JPG)
Serious Eats / Amanda Suarez
Now, make a series of vertical cuts, running from the stem end towards the root end (along the Y-axis). Space these cuts similarly to your horizontal cuts, again according to your desired dice size. Crucially, keep the root end intact. To protect your fingers, use the “claw grip” technique: curl your fingers inwards, keeping your fingertips tucked behind your knuckles and your thumb safely behind your fingers. Use your knuckles as a guide for the knife blade, ensuring consistent and safe strokes.
Step 6: Dice Across (X-Axis)
:max_bytes(150000):strip_icc()/20220511-CuttingOnions-AmandaSuarez-_18-7fde834f898e4dd097e90309248dde3d.JPG)
Serious Eats / Amanda Suarez
Finally, to create the dice, make vertical cuts perpendicular to the previous vertical cuts (along the X-axis). Continue using your knuckle as a guide for your blade, maintaining consistent spacing for uniform dice. As you approach the root end, you can rotate the onion forward by 90 degrees to present a more stable cutting surface. Continue dicing until you reach the root end; discard the root.
Step 7: Transferring the Diced Onion
Avoid using the sharp edge of your knife to scoop up diced vegetables. Dragging the blade across the cutting board will quickly dull its edge. Instead, use a bench scraper. This kitchen tool is specifically designed for efficiently and safely transferring chopped ingredients.
Achieving Fine and Medium Dice
:max_bytes(150000):strip_icc()/20220511-CuttingOnions-AmandaSuarez-_271-b66ae42f910e4af3b9fc5a621f0ea1d4.JPG)
Serious Eats / Amanda Suarez
The spacing between your horizontal and vertical cuts determines the final size of your dice. For large dice, space cuts approximately three-quarters to one inch apart. For medium dice, aim for half-inch spacing. For fine dice, cuts should be about a quarter inch apart or even smaller. For brunoise, the smallest dice, cut as finely as possible, requiring a very sharp knife and a steady hand for cuts as small as an eighth or even a sixteenth of an inch.
The Safer Way to Dice Onions: Minimizing Kitchen Accidents
Kitchen knife accidents are unfortunately common. While accepting that minor nicks can happen, it’s crucial to minimize risk, especially when performing repetitive knife work like dicing onions. Several common factors contribute to kitchen cuts and can be easily addressed: using dull knives (which should be regularly sharpened), improper knife handling techniques, unstable ingredients, wobbly cutting boards (which can be stabilized), and rushing while distracted. Simply focusing on the task at hand significantly reduces the chance of injury.
One particularly effective way to reduce the risk of cuts when dicing onions is to eliminate horizontal knife strokes directed towards your non-dominant hand or body. Horizontal cuts, especially those used in the traditional onion dicing method, are a frequent cause of kitchen injuries, second only to failed avocado pit extractions. Fortunately, a safer method exists that avoids these risky parallel-to-the-cutting-board cuts. Here’s how to dice onions more safely:
Step 1: Quarter the Onion Through the Root End
:max_bytes(150000):strip_icc()/optaboutcomcoeusresourcescontent_migration__serious_eatsseriouseats.com202101__20201027-quarter-dice-onions-vicky-wasik-1-d40adbc42d76408da8a15ec2b03f3df2.jpg)
Serious Eats
Begin as you would for the traditional dice: trim the stem end and halve the onion through the root. Then, placing each half cut-side down, slice them in half again through the root end, resulting in four onion quarters.
Step 2: Peel the Outer Layers from Each Quarter
:max_bytes(150000):strip_icc()/optaboutcomcoeusresourcescontent_migration__serious_eatsseriouseats.com202101__20201027-quarter-dice-onions-vicky-wasik-2-1e886654abc14c2997ef31e06db22a51.jpg)
Serious Eats
Similar to the traditional method, peel off the outer skin and the dry, pale layer immediately underneath from each onion quarter.
Step 3: Make the First Set of Vertical (Y-Axis) Cuts
:max_bytes(150000):strip_icc()/optaboutcomcoeusresourcescontent_migration__serious_eatsseriouseats.com202101__20201027-quarter-dice-onions-vicky-wasik-4-750b52a3994e42ca98b7773795c46abc.jpg)
Serious Eats
Working with one onion quarter at a time, make a series of evenly spaced vertical cuts from the stem end towards (but not through) the root end. Use the claw grip with your non-dominant hand and your knuckles as a guide for safe, consistent knife strokes.
Step 4: Rotate the Quarter 90 Degrees
:max_bytes(150000):strip_icc()/optaboutcomcoeusresourcescontent_migration__serious_eatsseriouseats.com202101__20201027-quarter-dice-onions-vicky-wasik-5.jpg-20201027-quarter-dice-onions-vicky-wasik-collage-f47e5c49bcb84e61938db2d0afedbc18.jpg)
Serious Eats
Rotate the onion quarter 90 degrees onto its adjacent flat side. The vertical cuts you just made will now be oriented horizontally (along what is now the X-axis).
Step 5: Make the Second Set of Vertical (New Y-Axis) Cuts
:max_bytes(150000):strip_icc()/optaboutcomcoeusresourcescontent_migration__serious_eatsseriouseats.com202101__20201027-quarter-dice-onions-vicky-wasik-7-9fb31994e4094afb8df2ecbd360b4e0b.jpg)
Serious Eats
Make a second set of vertical cuts, again evenly spaced and running from the stem end towards the root end. Align these cuts with the same spacing as the first set, maintaining the root end’s integrity.
Step 6: Final Dice (X-Axis) Cuts
:max_bytes(150000):strip_icc()/optaboutcomcoeusresourcescontent_migration__serious_eatsseriouseats.com202101__20201027-quarter-dice-onions-vicky-wasik-9-e03325f40cfe446787b08b8aca291479.jpg)
Serious Eats
Complete the dicing process by making a final series of vertical cuts, perpendicular to the previous set. Use your knuckles to guide the knife for consistent strokes. Admire your perfectly diced onions, achieved without any horizontal cuts directed towards your hand!
How to Slice Onions: Rings, Half-Rings, and Pole-to-Pole Slices
Understanding how to slice onions is as important as dicing them. The direction of your slices significantly impacts both the flavor and texture of the cooked onion. Onion cells are elongated, and slicing from the stem end to the root end (pole-to-pole) ruptures fewer cells compared to slicing across the equator. Since the pungent aroma and flavor of onions are released when cells are ruptured, pole-to-pole slicing results in milder, sweeter slices.
To illustrate this, try a simple experiment: slice one onion half pole-to-pole and the other half parallel to the equator. Place each in a sealed container for 15 minutes. Then, open and smell each container. You’ll notice that the pole-to-pole sliced onion has a significantly milder aroma. This difference translates directly to your cooking.
Texturally, equatorially sliced onions are less desirable for cooked dishes. They tend to cook unevenly and can become stringy or wormy. Their primary use is in raw applications where a strong, pungent onion flavor is desired, such as in salads or sandwiches, or when a round shape is specifically needed, like for onion rings.
For most recipes calling for sliced onions, pole-to-pole slices are preferred. They cook more evenly, become tender more readily, and when cooked for a long time, they break down almost completely, adding body and richness to soups, stews, and braises.
Cutting Onion Rings and Half Rings
:max_bytes(150000):strip_icc()/20220511-CuttingOnions-AmandaSuarez-_49-5d1366122af14036b34827d67e1a65c3.JPG)
Serious Eats / Amanda Suarez
To cut onion rings or half rings, simply peel the onion as you would for dicing. Then, slice across the onion, parallel to the equator, using your knuckles as a guide for consistent thickness. If slicing a whole onion, hold it firmly with your fingertips to maintain stability.
Slicing Onions Pole-to-Pole for Cooking: Step 1 – Trim the Root End
:max_bytes(150000):strip_icc()/20220511-CuttingOnions-AmandaSuarez-_6-b1735ebbef004f579071c349c78cc50d.JPG)
Serious Eats / Amanda Suarez
After trimming the stem end and halving the onion as you would for dicing, turn the onion half around and trim off the root end as well. Peeling is best done after trimming both ends for slicing.
Slicing Onions Pole-to-Pole for Cooking: Step 2 – Slice
:max_bytes(150000):strip_icc()/20220511-CuttingOnions-AmandaSuarez-_60-69b785a2af8540e5b529e6749209101a.JPG)
Serious Eats / Amanda Suarez
Make a series of slices perpendicular to the equator of the onion (pole-to-pole), running from the stem end to where the root was. Again, use your knuckles of your non-knife hand as a guide for consistent slices.
:max_bytes(150000):strip_icc()/20220511-CuttingOnions-AmandaSuarez-_61-21a5c44ecc714137b0b192538b7edd0b.JPG)
Serious Eats / Amanda Suarez
Pro Tips for Efficient Onion Preparation
When working with a large quantity of onions, streamline the process by batch processing each step. For example, peel all your onions first before beginning any slicing or dicing. Similarly, complete all horizontal cuts before moving to vertical cuts. This approach keeps your workspace more organized, reduces waste trips to the compost bin, and enhances your efficiency in the kitchen, making you work like a professional.
If you plan to serve onions raw and wish to reduce their pungency, place the sliced onions in a strainer and rinse them under hot running water. Hot water is more effective at washing away the lacrimators—the compounds that cause tearing when cutting onions—without softening the onion’s texture. Also, avoid letting sliced onions sit for too long; they become more pungent as they rest.
Regarding onion-induced tears, numerous home remedies exist, from chewing gum to placing bread nearby. However, most are ineffective. The most reliable solution is to create a physical barrier to protect your eyes. Contact lens wearers often experience some protection. Otherwise, inexpensive kitchen goggles are a very effective solution. At the very least, positioning a fan to blow the onion fumes away from your face can offer some relief. And remember, while the tears might be real, onions don’t feel pain—so there’s truly nothing to cry about!
Choosing the right onion for the right purpose is also key. For a comprehensive guide, refer to our Beginner’s Guide to Onions for a detailed exploration of different onion varieties and their best culinary applications.
This post from J. Kenji López-Alt has been updated with an additional section (“A Safer Way to Dice Onions”) from Sasha Marx.
