How to Dice an Onion in 30 Seconds

Kitchen Tips and Tricks -Part 2

Onions are my favorite vegetable to cut! It didn’t always used to be this way. Before culinary school I had no idea how to handle an onion. Then in school I learned an advanced way to cut an onion but it involved cutting horizontally and I was always scared to cut myself. After working in the industry I learned an even easier way!

Step 1

First we need to get a flat side to safely cut the onion and also to remove the peel easier. Hold the onion firmly and cut both ends off. Leave some of the root core in tact so the onion stays together when you cut it- you’ll see in step 3 what I mean. (Cut the dirty roots off but leave that core inside the peel in tact).

Step 2

Turn the onion on a flat side root side up and cut it in half vertically. Then peel the onion.

Step 3

Lay the onion with it’s large flat side down and the root part of the onion away from you. Beginning on one side of the onion use the tip part of your knife to begin cutting about 3/4 of the way away from the far end and make a downward motion to cut all the way through the end closest to you (don’t begin the cut completely at the far end because we want the onion to stay intact). See the photo.

Repeat this in the width that you wish your dice to be.

Step 4

Turn the onion 90 degrees. Begin cutting the onion crosswise. How far apart you make your cuts will depend again on the width of your dice you wish to achieve.

Repeat with the other half of the onion.

And there you have it, diced onion! There will be some odd pieces from the sides of the onion but just roll with it. Pat yourself on the back and enjoy not having to cry about cutting onions anymore. 😉

TIP: For optimal nutrient absorption let your cut onions sit for at least 5-10 minutes. Onions, like garlic, contain beneficial sulfur-containing compounds. Upon cutting and exposing to oxygen these phytonutrients are converted into compounds that promote health! The longer it sits, the more these compounds are converted. Heat deactivates these compounds so the that is why it is best to let them sit as long as possible to build up a fighting a chance of the phytonutrients surviving cooking. Also the finer the cut the better!

Why do Onions make my eyes water? Make it stop!

Onions contain two compounds called allin and allinase. When the onion is whole these compounds are separate but when the onion is cut the cell walls are ruptured allowing these two compounds to combine and form a new compound called thiopropanal sulfoxide. Like discussed above this compound increases the onions’ health promoting properties, but is also responsible for the pungent taste and aroma, as well as making our eyes water when it gets in the air. Some tricks that can help prevent your eyes from watering are cutting near a running vent, open window, or chilling the onion for an hour before cutting it. Running the onion under water will decrease its nutrition.

Nutrition of Onions

Which type of onions are the healthiest? It seems red onions rich in their flavonoid antioxidants that help prevent cancer and heart disease among many other chronic illnesses are the most nutrient dense. Rule of thumb the richer the color of any vegetable the more nutrients. Research supports that onions are beneficial for promoting blood sugar balance, heart health, digestive health, immune health, and preventing inflammation. This is all because onions are rich in vitamins and minerals such as vitamin b6, quercetin, folate, biotin, chromium, phosphorus, potassium, copper, as well as the amino acid tryptophan which is needed for sleep! I found it most interesting that cooking meat with onions helps neutralize some of the free radicals that occur from cooking meat at a high heat. Plus they add such great flavor! It is recommended in the book The World’s Healthiest Foods by George Mateljan to consume at least two onions a week following the guidelines above to get the best health benefits! If you want to read more in depth about the nutrition of onions you can go to his website:

How to Store Onions

Properly stored, onions can last for a month or more. It is most important to make sure they are in a ventilated area and are stored in something such as perforated basket that allows air to circulate underneath. Yellow onions will last longer than white onions because they contain more of those pungent compounds discussed above. DO NOT refrigerate uncut onions. The moisture in the refrigerator will cause spoilage. Make sure they are in a dry and dark place for long term storage. The only exception is green onions, also known as scallions. Those should be stored in the refrigerator in a plastic bag wrapped tightly around them. Also store away from potatoes. They will absorb the potatoes’ moisture and the ethylene gas from potatoes will cause spoilage as it is a ripening compound.

Sometimes we don’t need the whole onion. Cut onions should be stored in the refrigerator in an airtight container an used within 2 days as the onion will begin to oxidize.

I hope you found this post helpful and healthful!



Resources The World’s Healthiest Foods by George Mateljan first edition


Published by Abigail E. Holistic

Holistic Health Coach and Private Chef

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