What is Onion? All You Need to Know About This Versatile Vegetable

by Joost Nusselder | Last Updated:  May 28, 2022

Always the latest smoking tips & tricks?

Subscribe to THE ESSENTIAL newsletter for aspiring pitmasters

We'll only use your email address for our newsletter and respect your privacy

I love creating free content full of tips for my readers, you. I don't accept paid sponsorships, my opinion is my own, but if you find my recommendations helpful and you end up buying something you like through one of my links, I could earn a commission at no extra cost to you. Learn more

Onion is a versatile vegetable that’s a staple in many cuisines worldwide. It belongs to the lily family and is closely related to garlic and chives. As a base ingredient, it’s used in soups, stews, sauces, dips, and more. It’s also a popular addition to salads, sandwiches, and other dishes.

In this article, we’ll explore the many uses of onion, and of course, its delicious flavor.

What is an onion

The Many Facets of the Humble Onion

Onions are round vegetables with a light brown skin, typically 2-3 inches in diameter. They are composed of numerous white layers, or scales, that are usually topped with a rounded, leaf-like structure. The outermost layer is thin and papery, while the inner layers are thicker and more fibrous. The center of the onion is composed of a hard, compacted material that is rich in carbohydrates and other compounds. Onions can be found in a range of colors, including white, yellow, red, and even bluish-black.

Forms and Varieties of Onions

Onions come in many different forms and varieties, each with its own unique characteristics. Some of the most common forms of onions include:

  • Dry onions: These are the most widely grown and consumed type of onion. They are typically used in cooking and can be stored for long periods of time.
  • Green onions: Also known as scallions, these onions are harvested before they fully mature and are typically used in salads and other raw dishes.
  • Shallots: These are small, elongated onions with a mild, sweet flavor. They are often used in French cuisine.
  • Pearl onions: These are small, round onions that are typically used in stews and other slow-cooked dishes.

Growing Onions

Onions are typically grown as an annual crop, although some varieties can be grown as perennials in warmer climates. They are part of the allium family of plants, which also includes garlic and leeks. Onions grow from bulbs, which are usually planted directly in the soil. The bulbs develop a fibrous root system and a stem, which begins to grow and produce leaves. As the plant matures, it develops an inflorescence, or flowering stem, which produces flowers and eventually seeds. However, most commercial onion growers will remove the flowering stem to encourage the bulb to swell.

Uses of Onions

Onions are a versatile food that can be used in a wide range of dishes. They are known for their sharp, pungent flavor and are often used to add depth and complexity to savory dishes. Some common uses of onions include:

  • Chopping and sautéing onions as a base for soups, stews, and sauces.
  • Adding raw onions to salads and sandwiches.
  • Grilling or roasting onions as a side dish.
  • Pickling onions to preserve them for later use.

Health Benefits of Onions

Onions are a great source of vitamins and minerals, including vitamin C, vitamin B6, and potassium. They are also rich in antioxidants and other compounds that have been associated with a range of health benefits, including:

  • Lowering blood pressure and reducing the risk of heart disease.
  • Reducing inflammation and improving immune function.
  • Helping to regulate blood sugar levels.

Exploring the Wonderful World of Onion Types

For people who want a delicate and mild flavor, sweet onion types are the best choice. These onions are known for their low sulfur content, which means they don’t have the sharp, strong taste that other onion types have. They are ideal for making salads, sandwiches, and soups. Some of the most famous sweet onion types include:

  • Vidalia onions
  • Maui onions
  • Walla Walla onions

These onions are widely known for their sweet taste and are often sliced and served raw in salads or marinated and pickled for a complex flavor kick. Chefs suggest using them in recipes that need a lot of onions, as they are not as strong as other types.

The Many Uses of Onion: From Seasoning to Medicine

  • Onions are commonly eaten as food and can be prepared in many ways, such as sautéed, caramelized, grilled, or fried.
  • One of the best ways to store onions is in a cool, dry place away from other produce, as they can release gases that may cause spoilage.
  • Some people may pose an allergy or intolerance to onions, which can cause symptoms such as hives, itching, or difficulty breathing. If you experience any of these symptoms after eating onions, seek medical attention immediately.

Seasoning and Enhancing Flavors

  • Onions are a staple ingredient in many soups, stews, and sauces, adding depth and flavor to the dish.
  • Leeks, a close relative of onions, can also be used in many recipes to add a milder onion flavor.
  • Onions can be seasoned à la française, with breadcrumbs and Gruyère cheese, and baked to create a delicious side dish.
  • When cooked, the onion mellows in flavor and softens, making it a versatile ingredient in many dishes.

Medicinal Properties of Onion

  • Onion extract contains chemicals that may reduce swelling and lung tightness related to asthma.
  • Onions also contain chemicals that may reduce cholesterol and lower blood sugar levels.
  • Some people use onion to prevent scarring, although more research is needed to confirm this claim.
  • While onions have many health benefits, they may also pose risks for some individuals, such as those with onion allergies or intolerances.

Storing Onions: Keep Them Fresh and Flavorful

When it comes to storing onions, choosing the right type is important. Not all onions are created equal, and some are better suited for long-term storage than others. Here are some tips for choosing onions to store:

  • Choose onions that are firm, dry, and free of soft spots or blemishes.
  • Look for onions with papery skins that are tightly wrapped around the onion.
  • Choose onions that have been cured properly. Curing is the process of drying the onions after they are harvested, which helps to extend their shelf life.

Inspecting Onions Before Storage

Before storing onions, it’s important to inspect them carefully to ensure they are in good condition. Here are some things to look for:

  • Check for any signs of mold or spoilage. If an onion is soft or has a foul odor, discard it.
  • Look for any signs of sprouting. Sprouting is a natural process that causes onions to emit a gas that can cause other onions to sprout and spoil.
  • Check for any signs of damage or bruising. Onions that are damaged or bruised are more prone to spoilage and should be used up quickly.

Methods for Storing Onions

There are several methods for storing onions, but the most important thing is to keep them in a dry, well-ventilated place. Here are some simple instructions for storing onions:

  • Choose a location that is cool, dark, and dry. Moisture and light can shorten the life of stored onions, so it’s important to keep them in a dry environment.
  • Store onions in a mesh bag or wooden box. These containers allow air to circulate around the onions, which helps to prevent mold and sprouting.
  • Avoid storing onions in a damp environment, such as a basement or garage. This can cause the onions to become soft and spoil.
  • Don’t store onions in the fridge. Onions are prone to absorbing moisture and odors, which can cause them to become soft and bitter.

By following these simple tips for storing onions, you can keep them fresh and flavorful for weeks or even months.

Why Onions are a Must-Have in Your Diet

Onions are a type of vegetable that contains a wide range of organic sulfur compounds. These compounds are the reason behind the strong taste and smell of onions. However, they also offer a range of positive effects on the body, including:

  • Reducing the level of cholesterol in your body
  • Breaking down blood clots, lowering your risk for heart disease and stroke
  • Preventing certain types of cancer, such as colorectal cancer
  • Acting as an antioxidant, which helps to maintain the structure of your body’s cells

Research has found that onions offer a range of potential benefits

According to research, the consumption of onions, both raw and cooked, can have a range of positive effects on the body. Some of the benefits of eating onions include:

  • Lowering blood pressure
  • Reducing the risk of heart attack
  • Lowering the risk of certain types of cancer
  • Providing essential vitamins and minerals, including vitamin C, vitamin B6, and folate
  • Offering a low-carbohydrate food option for those following a low-carb diet

Onions come in a variety of types and can be cooked in different ways

There are many different types of onions, including white, yellow, and sweet onions. Each type has a slightly different taste and can be used in a variety of dishes. Onions can be eaten raw or cooked, and can be steamed, roasted, or sautéed. Depending on how they are cooked, onions can have different levels of beneficial compounds.

Onions are highly recommended for heart health

One of the biggest benefits of onions is their potential to reduce the risk of heart disease. According to a review of research, consuming onions can help to:

  • Lower blood pressure
  • Reduce the risk of heart attack
  • Lower cholesterol levels

Consuming onions can help with weight maintenance

Onions are an excellent food choice for those looking to maintain a healthy weight. They are low in calories and high in fiber, meaning they can help you feel full for longer periods of time. Additionally, the compounds found in onions may help to reduce inflammation in the body, which is important for weight maintenance.

Onions are a rich source of essential nutrients

Onions are packed with essential vitamins and minerals, including vitamin C, vitamin B6, and folate. They also contain a range of beneficial compounds, including organic sulfur compounds, which are important for building and maintaining a healthy body.

Chopping onions may cause tears, but it’s worth it

Chopping onions can be a tear-inducing experience, but the benefits of consuming onions far outweigh the temporary discomfort. To reduce the tears caused by chopping onions, it is advised to chill the onion in the refrigerator before chopping or to chop the onion under running water.

Note: Onions are a member of the allium family, which includes garlic, shallots, and leeks. These foods offer similar health benefits to onions and are also highly recommended for consumption.

Onion Nutrition: The Low-Calorie Vegetable with High Health Benefits

Onions are a widely cultivated vegetable that is classified as a low-calorie food. A medium-sized onion contains approximately 44 calories, 0.1 grams of fat, 1.1 grams of protein, and 10 grams of carbohydrates. The following are the main nutritional components of onions:

  • Fiber: Onions are a decent source of fiber, providing approximately 1.7 grams per 100 grams of raw onion. Fiber is essential for maintaining a healthy digestive system and can help lower the risk of heart disease.
  • Vitamin C: A medium-sized onion contains approximately 6.5 milligrams of vitamin C, which is about 7 percent of the daily recommended intake. Vitamin C is an antioxidant that helps protect the body from damage caused by free radicals.
  • Folate: Onions are a good source of folate, providing approximately 10 percent of the daily recommended intake per medium-sized onion. Folate is essential for creating new cells and can help lower the risk of certain birth defects.
  • Quercetin: Onions contain a compound called quercetin, which has been found to have anti-inflammatory and antioxidant properties. Quercetin may also help improve heart health by lowering blood pressure and reducing cholesterol levels.

The Negative Effects of Onion Consumption

While onions are generally considered a healthy food, there are some negative effects of consuming onions, including:

  • Causing tears: Chopping onions can cause tears due to the release of a gas called syn-propanethial-S-oxide.
  • Creating bad breath: Onions contain compounds that can cause bad breath.
  • Sensitive stomachs: Some people may experience digestive issues after consuming onions, such as bloating and gas.

A Guide to Adding Onions to Your Diet

Onions are a versatile vegetable that can be prepared in a variety of ways, including raw, cooked, and sliced. The following are some tips for adding onions to your diet:

  • Raw: Add sliced onions to salads or sandwiches for a crunchy texture and a little bit of spice.
  • Cooked: Saute onions with other vegetables for a flavorful side dish or add them to soups and stews for added depth of flavor.
  • Sliced: Use thinly sliced onions as a topping for burgers or tacos for a little bit of crunch and a lot of flavor.

Overall, onions are a low-calorie food that is rich in essential nutrients and compounds that can improve overall health. Whether you prefer them raw, cooked, or sliced, adding onions to your diet can help you reap the many health benefits they provide.

Why Do Onions Make You Cry?

Onions are made up of different compounds, including amino acids and sulfuric acid. When an onion is sliced or diced, the onion’s cells release these compounds into the air. This is where the trouble begins.

The Role of Enzymes

When the onion’s compounds are released into the air, an enzyme called alliinase is activated. This enzyme works to alter the amino acids into lachrymator compounds. This form of sulfuric acid irritates the nerves around the eyes, making them tear up.

How to Avoid Onion Tears

While it may seem impossible to avoid onion tears altogether, there are a few tricks you can try to minimize the amount of tears you shed:

  • Chill the onion in the refrigerator before cutting it. This can help slow down the release of the irritating compounds.
  • Cut the onion under running water. This can help wash away the compounds before they can irritate your eyes.
  • Wear goggles or glasses while chopping onions. This will create a barrier between your eyes and the onion’s compounds.


So there you have it, the many uses of the onion and why it’s such a versatile ingredient. 

You can use them in almost any dish, from savory to sweet, and they’re great for your health too. So don’t be afraid to add them to your next recipe!

Joost Nusselder, the founder of Lakeside Smokers is a content marketer, dad and loves trying out new food with BBQ Smoking (& Japanese food!) at the heart of his passion, and together with his team he's been creating in-depth blog articles since 2016 to help loyal readers with recipes and cooking tips.