What Are Onions? How to Prep, Cook, Store Onions

Like garlic, onions are powerhouses of flavor. You can enjoy them raw or cooked to add depth to your dish. Onions are essential in your everyday pantry. Learn about the different types of onions, how to prepare them, and how to substitute them in a pinch.

A variety of onions including yellow onion, white onion, sweet onion, red onion, green onion, and shallot

What Are Onions?

The onion is an aromatic root vegetable that is widely used in cuisines all over the world. It is an important foundation in flavoring your food, often serving as the aromatic base of your dish alongside carrots, celery, and bell peppers, such as in mirepoix and the holy trinity.

What Onions Look Like

Side-by-side view of whole bulb onions, sliced bulb onions, and sliced green onions to show the comparison

Types of Onions

You can eat the onion bulb and the leaves that sprout from the bulb (or roots in the case of green onions). Onion bulbs come in different colors and flavors. Although the bulbs differ in color and vary in crispness, sweetness, and spiciness, most onions taste very similar to me. I think it’s fine to use them interchangeably.

While some cooks may be opinionated that specific types of onion are only appropriate for certain dishes, I tend to save mental energy by using whatever onion is on hand (except for green onions, which taste noticeably different from onion bulbs).

Yellow Onion

A view of a yellow onion chopped in half to see the cross sectional view and the outer skin

The yellow onion is the general-purpose onion that you can use in stir fries, curries, soups, caramelizing, and broths. I like throwing half an onion into the Instant Pot when cooking dry beans. Yellow onions become golden and caramelized when sautéed and are featured in the French Onion Soup.

Because the yellow onion makes up almost 90% of the onions grown in the U.S., it is the least expensive type of onion. That’s why yellow onions are my first choice for caramelizing and putting into stews and soups, especially when you need a lot of onions. If your recipe doesn’t specify which type of onion, use the yellow onion.

Sweet Onion

A view of a sweet onion chopped in half to see the cross sectional view and the outer skin

The sweet onion is a type of yellow onion that is specially cultivated to have higher sugar content, such as the Vidalia, Walla Walla, and Cévennes varieties. Look for sweet onions if you’re making onion rings or caramelizing onions for a sweeter dish. 

White Onion

A view of a white onion chopped in half to see the cross sectional view and the outer skin

The white onion is milder and sweeter than the yellow onion but tangier and spicier than the red onion. The white onion still has a bite when raw. It is very common in Mexican cuisine and is the preferred type of onion for salsa and guacamole (if you like onion in yours). Due to its compact cell structure, it has a shorter shelf life than the yellow onion. Therefore, you may want to use it up sooner than your typical yellow onion.

Red Onion

A view of a red onion chopped in half to see the cross sectional view and the outer skin

The red onion is prized for its bright magenta color. Its bold appearance makes red onions a great addition thinly sliced on top of salads, burgers, and pizza. It is frequently served raw and finely minced in salad dressing.

Pearl Onion

The pearl onion is a baby onion that has not yet reached its mature size. You’ll frequently find pearl onions pickled or in cocktails (martinis). It also works well on skewers for grilling. You can buy pearl onions already peeled and frozen.

Green Onions

A view of a green onion chopped in half to see the cross sectional view and the outer skin

Green onions, also called scallions, offer a different flavor compared to the onion bulbs. Green onions taste crisper and more refreshing compared to the sweet, caramelized flavor of onion bulbs. Many types of green onions will not grow into a bulb even at maturity. The spring onion is the budding bulb with green sprouts harvested before the onion has matured into a large bulb.

The white parts near the roots have the most pungent flavor and offer great aroma to your stir fries, potato salads, and omelets. The green parts are beautiful for garnishing on top of leafy salads, tacos, and noodles. Green onions are a mainstay in Chinese cooking, appearing in stir fries, salad dressings, and seafood dishes.


To learn more about different varieties of onions, check out Serious Eats‘ guide that outlines a few more onion types than I covered here.

How to Prep Onion

Peel the onion’s tough outer skin and discard.

Similar to garlic, onions release their pungent flavor when their cells are crushed. You can control how strong garlic tastes based on how finely you chop onions.

From the least to the most pungent:

  • Halved or quartered: Cutting a bulb in half or into quarters is an easy way to add onion flavor without dealing with teary eyes. Halving or quartering is great for making broths, soups, and grilling
  • Roughly chopped: Great for stir fries, and braising
  • Sliced: Useful for garlic pizza, sauces (garlic pizza sauce), soups (Chas’ French Onion Soup), and stews like ratatouille because it can be faster than dicing or you want a sliced presentation
  • Diced: Goes well with other aromatic vegetables as the base for soups, stews like jambalaya, and sauces (tomato cream pasta sauce)
  • Minced: Ideal for salad dressing or topping salads
  • Grated: Even stronger than fine mincing, grated onion can be included in pasta sauces and white sauces
  • Blended: Some home cooks blend sauces, such as pizza sauce or pasta sauce, after cooking the onions to make the sauce very smooth. You can also blend green onions with cream cheese to make a herb dip.
Overhead view of chopped green onions for the Kari's Welcome Home Meat Sauce recipe

Here are two resources to help you chop an onion. Gordon Ramsey provides conventional guidance and The Spruce Eats has a differing opinion about avoiding horizontal slices to protect your fingers.

TIP: Skip to the FAQ for advice on how to reduce tears when chopping onions.

How to Eat Onion Raw

Because raw onions are very sharp, pungent, and spicy, raw onion bulbs are best served very finely sliced when raw. You can also finely mince them to add to salad dressings.

Green onions are commonly eaten raw where they add a moderately spicy and clean, crisp taste to your dish. You can roughly chop them or slice them thinly to garnish your dish.

How to Cook Onion

Onions can be a main ingredient. When cooked alone, they taste sweet, mild, rich and jammy. You can roast, grill, or sauté onions to make caramelized onion chutney or jam. You can deep fry them to make onion rings.

When cooking, you can slow-cook, braise, stew, stir fry, and stuff onions following your favorite recipes.

A view of caramelized onions next to brie and sliced bread

TIP: When caramelizing onions, use low or medium-low heat because high heat can accidentally burn the onions, which will ruin your caramelized onions. If you want to speed up the caramelization, put a lid on the pan and remove it when the onions are translucent so they have a chance to brown.

Onion Works Well With…

  • Creamy dips
  • Olive oil (caramelized onion)
  • Meats that are roasted, stewed, grilled or pan fried (steaks, meat sauces)
  • Stir frying with green vegetables (broccoli, cabbage, bok choy)
  • Summer vegetables (zucchini and eggplant in ratatouille)
  • Tomatoes (pizza sauce, pasta sauce)
  • Root vegetables e.g. carrots, potatoes, sweet potatoes (curry)
  • Soup and broths
  • Pizza (top your pizza with finely sliced or minced onion before baking)
  • Salad (top your salad with green onions or finely sliced onion)
  • Basically everything

Recipes With Onion

Chas’ French Onion Soup
Piping hot French Onion Soup is a great way to greet the cold winter weather. Watch the stale bread come back to life when coated with golden, bubbly gruyère and given a chance to soak up the delicious rich soup.
Get the Recipe
Chas' French Onion Soup // recipe from garlicdelight.com
5-Minute Garlic Herb Dip
Inspired by Boursin, this refreshing garlic dip provides a home for the leftover herbs in your fridge. Smear the garlic herb dip on your toasted bagel or crackers. Dip your celery and carrot sticks into this garlic dip.
Get the Recipe
Carrot stick dipped in the Garlic Herb Dip with cilantro for garnish.
Vegan Ratatouille with Eggplant and Zucchini
This simple, no-bake recipe makes a hearty pot of ratatouille that your vegan friends & family will love. The recipe is designed to feed a group of 6-8 (depending on serving size) or allow a family of 1-2 to have leftovers for 3-4 meals.
Get the Recipe
A medium view of ratatouille on a pink background with chamomile flowers and pink tongs

How to Substitute Onion

Shallots

A view of a shallot chopped in half to see the cross sectional view and the outer skin

Shallots are not onions but closely related cousins. Shallots are sweeter, richer, and stronger than the typical onion bulb, which makes them a premium substitute for the onion.

They are frequently served in French cooking used in salad dressings and roasting chicken. You’ll find shallots deep-fried in Asian cooking, such as on top of pan-fried noodles.

Shallots are much more expensive than the yellow onion, so I only use shallots in salad dressings or thinly sliced raw where I can taste the shallot. A jumbo onion is the size of 3 to 4 shallots, so you can substitute onions and shallots accordingly.

Leeks

Leeks are not onions but closely related cousins in the allium family. If you’re missing onions or green onions, you can substitute leeks, especially in Chinese cooking, which uses baby leek greens in seafood in addition to or in place of green onions.


If you’re out of green onions for a stir fry, you can substitute with garlic and/or ginger.

Where To Buy Onion

You can find fresh onions at any grocery store in the produce section, usually next to the other alliums like garlic and the root vegetables. The onion powder is usually in the spice aisle. Jars of pickled onions are usually in the canned vegetable aisle. Frozen pearl onions are in the freezer section.

Are Onions Seasonal?

Onions are seasonal. You can find spring onions during the spring before the bulbs have matured, which typically takes place during the summer. Thanks to how well onions store and importing, you can enjoy onions year-round.

How to Store Onion

Fresh raw onions should be stored whole in a dark, dry, and cool place in a breathable bag or a basket. They can live with garlic and other root vegetables. Under the sink or in your pantry in a netted bag are ideal storage conditions.

A bag of onions in its original mesh bag
A bag of onions in its original mesh bag. Store them in a similar breathable bag or in a basket.

You can peel and chop onions on the weekends to prepare them so that you can cook dinner faster during the week. Chop the onions into a variety of sizes and store them in a glass container. They will last a week chopped.

Fun Things To Do With Onion  

Hold your nose and bite into an onion. Can you tell it’s an onion and not an apple? Your nose registers much of the onion’s flavor.

Unrelated to cooking, you can check out The Onion if you’re ever looking for a good laugh.

You can sprout an onions by leaving it on your kitchen counter until it grows green shoots. Then put the onion bulb in water and watch it continue growing shoots. You can snip off the shoots and use them as green onions.

FAQ About Onion  

Why Do Onions Make You Cry?

Onions have sulfuric compounds (specifically syn-Propanethial-S-oxide) that act as “lachrymatory agents”, meaning they trigger your eyes to tear up. It appears to be the onion’s natural defense against predators.

How to Cut Onions Without Tears?

I found The Kitchn article with tips on how to chop onions without tears helpful. I’ve tried using swim goggles to cut onions, and they worked. My eyes didn’t tear up, but the foggy goggles made it hard to see, which was impractical. So I’d suggest the freezer method or the vent hood. Walking away for 2 minutes to take a break helps too.

If cutting raw onions still bothers your eyes after trying those tips, use onion powder.

Anna looking down chopping vegetables
About Anna Rider

Hi! I'm Anna, a food writer who documents kitchen experiments on GarlicDelight.com with the help of my physicist and taste-testing husband, Alex. I have an insatiable appetite for noodles 🍜 and believe in "improv cooking".

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