How to Dice an Onion Effortlessly (and Save Your Fingers in the Process)

Onions are the behind-the-scenes showrunners of many a dish, adding savory depth and mellow sweetness. So when a recipe calls for “one large onion, diced,” why do we all shudder in fear? Probably because dicing an onion can be a real pain. Which way do you slice first? Do you leave the root on? And what’s the deal with the peel? Yes, we’re crying, and no, it’s not just the onion.

But there’s a method for dicing onions that, once you it commit to memory, will save you time in the kitchen and keep you from tears (not literally, sorry). In fact, it’s the method our food editor endorses for efficiency and safety, and it also works for garlic cloves and scallions. Here’s how to dice an onion in four easy steps and without any trips to the ER.

Spanish, Vidalia, Pearl—What’s the Difference Between Onions Anyway?

how to dice and onion step 1

1. Trim The Root End And Slice The Onion In Half

Using a recently sharpened chef’s knife, trim away and discard the dried, stringy root bits (but leave the root intact) so they don’t get mixed into your onion dice. Then, using one hand to stabilize the onion (fingers curled under), slice through the onion from pole end to pole end. (In other words, slice through either the root end or stem end to the opposite side.) Peel away the papery skin. (You can compost it or save it for homemade stock!)

how to dice an onion step 2

2. Make Three Or Four Horizontal Cuts Through Each Onion Half

With the flat side of the halved onion resting on your cutting board, hold your knife parallel to your work surface and make three or four horizontal cuts through the onion half, starting at the stem end and stopping before you reach the root. (Be mindful of keeping your fingers out of the way.) Repeat with the other half.

how to dice an onion step 3

3. Make Vertical Cuts Across Each Onion Half

Holding your knife perpendicular to your work surface, make vertical cuts across the onion half from stem end to root end. Repeat with the other half.

how to dice an onion step 4

4. Cut Across The Onion To Dice It

Rotate the onion half so the root end is in your nondominant hand and your knife is perpendicular to the root. With your fingertips tucked in and securely holding the onion, cut across the onion to dice it. Repeat with the other half.

Tips to Make Dicing an Onion Easier, Safer and Faster

Use the right knife. Choose a knife that’s large enough to slice through the onion with some leverage. We like to use a chef’s knife; a paring knife won’t be big enough unless your onion is very small.

Use a sharp knife. A recently sharpened knife is always safer than a dull one because you won’t have to use so much force to make clean cuts.

Tuck your fingers. Use the chef-approved knife skill technique that will safeguard your precious digits: Keep your fingertips curled under while stabilizing the onion. When making the horizontal cuts in step two, tuck your fingertips in while simultaneously pressing them against the top of the onion to keep it from sliding. 


Senior Food Editor

Katherine Gillen is PureWow’s senior food editor. She’s a writer, recipe developer and food stylist with a degree in culinary arts and professional experience in New York City...