🔪 Knife Skills · Lesson 3 of 5
How to Dice an Onion Fast, With Fewer Tears
Leave the root on, make three sets of cuts and an onion turns into an even dice in about a minute.
🎬 Watch the lesson
- Root left on
- Cuts toward the root, stopping short
- Cuts parallel to the board
- Cuts across make the dice
Why it matters
Onion starts a huge share of savory recipes, so this one skill pays off week after week. Most people peel it, chop it in random directions and chase the pieces around the board. The culinary school method keeps the onion in one piece until the very last cut.
The root is your handle
Cut the onion in half through the root and leave the root on each half. It holds the layers together while you cut and gives your guiding hand something to hold that's far from the blade.
Three sets of cuts
First, cuts from the stem end toward the root, stopping short of it. Second, one or two cuts parallel to the board. Third, cuts straight across. Each set is one direction of the cube.
The spacing sets the size
Space the first cuts about 1/4 inch apart for a small dice or 1/2 inch apart for a medium dice, and match that spacing on the cuts across.
Why your eyes sting
Cutting breaks the onion's cells and lets an enzyme turn its sulfur compounds into a gas, syn-propanethial S-oxide, that makes your eyes water. A sharp knife slices through cells instead of crushing them. Onion growers add that the root end holds the most of these compounds, one more reason to leave it whole.
Step by step
Cut off the stem end, the pointed top, and leave the root end on.
Cut the onion in half from top to root, through the root.
Peel off the skin and the first papery layer from each half.
Lay one half flat side down with the root pointing away from your knife hand.
Make evenly spaced cuts from the stem end toward the root, stopping about 1/2 inch short of it.
Hold the top with a flat hand and make one or two cuts parallel to the board toward the root, again stopping short.
Switch to the claw and cut straight across the onion, the same spacing apart, working toward the root.
When you reach the root, slice off what's left around it and keep the root for stock.
Common mistakes
- Cutting off the root first: the layers fall apart and slide around, so leave it on until the end.
- Cutting through the root on the first set of cuts: the onion splits into wedges, so stop about 1/2 inch short.
- Making the cuts parallel to the board with your hand underneath: keep the hand flat on top, fingers raised away from the edge.
- Using a dull knife: it crushes the onion, which means more tears and soggy pieces, so hone the knife first.
- Uneven spacing: big and small pieces brown at different speeds, so keep the cuts the same distance apart.
🏋️ Try it tonight
Buy a 3-pound bag of yellow onions and dice two of them tonight, one slow and careful, the second at your normal pace, keeping the root on both times. Cook both in a little butter over medium-low heat for 15 minutes and freeze what you don't use in a bag for next week's chili or soup.
💡 Did you know?
An onion doesn't contain its tear gas until you cut it: breaking the cells starts the enzyme reaction that makes the gas on the spot.
Use it tonight
Mujaddara (Lentils and Rice with Browned Onions)
The Levant's thrifty lentil and rice pilaf in one pot: a mountain of onions browned slowly in olive oil, half saved for the top, the rest cooked with cumin, coriander, brown lentils and rice. Meatless, with a cool lemon yogurt on the side.
Chili con Carne with Beans
The American home classic: ground beef, kidney beans and tomatoes simmered two hours with chili powder, cumin and a little heat.
The Oklahoma Fried Onion Burger
A small ball of beef smashed thin on a hot skillet with a mound of paper-thin onions pressed into it, flipped so the onions fry and caramelize, then topped with American cheese and a bun steamed right over the onions.
30-Minute Weeknight Beef and Bean Chili
Ground beef, kidney beans and lightly blitzed tomatoes with chili powder, cumin and a little chipotle, on the table in about 30 minutes.