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Spanish Onions: The Differences Between Them And Sweet, Red, White, And Yellow Onions

Dishes from around the world are always going to be different from one another, with some utilizing unique flavors and others making use of the simplest of ingredients.

However, for many dishes and cultures from around the world, one ingredient normally appears in some form or another on the plate.

Spanish Onions: The Differences Between Them And Sweet, Red, White, And Yellow Onions

That ingredient is the humble onion, a pungent, sweet root vegetable that has become synonymous with being the foundation of many cooked meals. However, there are many different kinds of onions and they each have a unique and delicious flavor.

In this article, we will explore the different kinds of onions and look at the differences between each of them, especially compared to the largest member of the onion family: the Spanish onion.

Types Of Onion

In truth, there are hundreds of different kinds of onions that exist on different branches of the onion family tree. However, of the common types of onion, there are generally 3 to 4 different types of onion that you will find on your grocery store shelf.

White Onions

White onions are probably the most mild of all the onion varieties. They have a sweet, soft flavor and are far less pungent than other onions, thanks to their high sugar and low sulfur content.

This allows them to be used as a backdrop to a lot of dishes, but also as a raw component in things like salads and sandwiches.

If you were to look for white onions in different cultures, you would most likely find them in European or Mexican cuisine, particularly in a variety of dishes that require delicate flavors like salsas and soups.

Yellow Onions

Yellow onions are the most common type of onion grown in temperate or colder climates, like in the US or Europe. They are incredibly rich in flavor and in scent, as they have a much higher sulfur content than other onions.

The incredibly rich and complex flavor has given rise to a number of dishes that are made with this onion in mind, such as French onion soup and caramelized onions.

Red Onions

Red onions are the most pungent of the onion family and have the most flavor out of them as well. They are sweet and incredibly sharp, with many describing their raw flavor and smell as ‘eye-watering’.

Unlike other onions, these ones don’t have a growing season and are available throughout the year.

Red onions are primarily used as the primary component of a dish or in incredibly rich dishes, as their flavor can hold its own against other very strong flavors.

They are a favorite for Indian cuisine, and you will often find them in curries rather than in other dishes.

So, What Are Spanish Onions, Then?

So, What Are Spanish Onions, Then?

Well, Spanish onions are simply a type of yellow onion, but the way they are grown makes them different from a lot of yellow onions. For starters, Spanish onions are planted in low-sulfur soil. This does two things.

The first is that it makes the onion’s flavor and smell less intense. An onion’s intensity in both flavor and scent is often decided when they are grown in a certain type of soil, with a sulfur rich soil giving a more intense onion than a sulfur poor soil.

The second thing that happens is that the onion becomes much sweeter. The lack of intensity of sharp flavors allows the onion’s natural sweetness to come to the surface and shine.

This makes them perfect for salads, soups, and sauces that align with the areas it is commonly grown – hot and humid places like the Mediterranean.

These conditions make these onions somewhat larger than their counterparts as well, but the main reason for growing yellow onions this way is flavor, rather than size.

Spanish Onion Vs Other Yellow Onion Varieties

The Spanish onion isn’t the only onion cultivated from a yellow onion origin, it is simply the oldest. In fact, the yellow onion has proved so versatile, that many different varieties have been grown.

The most well-known of these varieties is the Vidalia onion and the Walla Walla onion.

While the Spanish onion has been around for a long time, the Vidalia onion and the Walla Walla onion made their way onto the scene in the last 100 years.

The Walla Walla onion was bought by a former French soldier from Corsica in 1900 to the Walla Walla Valley in 1900. The onion was created by selectively breeding sweeter and sweeter onions from it.

Whereas, the Vidalia onions were first grown in the 1930s near Vidalia, Georgia, following the principles of the Spanish onion planting.

After many years, the Vidalia onion became a distinct tasting and smelling onion and a true Vidalia onion can only be obtained from a 20 county production region in Georgia today.

Both of these kinds of onion are from an original yellow onion source, but are nowadays referred to as sweet onions. Sweet onions are considered different from Spanish onions, and generally it is to do with their harvest times, storage, and a slight difference in taste.

For starters, sweet onions tend to also be called summer onions.

Where it is entirely possible to find a Spanish onion growing at any time of the year in your crop, a sweet onion will tend to only be harvestable during the summer months, making them a seasonal vegetable.

Sweet onions also store for less time than Spanish onions. They have a higher water content than Spanish onions, which means that they can rot or degrade quicker, especially if the summer is particularly hot and humid.

Finally, sweet onions are sweeter than Spanish onions, thanks to the selective breeding and pressures they are put under.

Since Spanish onions are already pretty sweet and are much sweeter than regular onions, this makes sweet onions quite distinctive in their flavor profile.

As you can see, there are few differences between Spanish and sweet onions, but they can both serve the same purpose as each other and act as a less intense alternative to the more pungent onions.

Best Ways To Serve Sweet And Spanish Onions

The thing with these onions is that their flavors and intensity are not overwhelming and will not dominate a meal. This gives them different options compared to their white, yellow, or red counterparts.

Slicing up these onions into rings and serving them raw is a great way to go, but you could also have them as a palate cleanser, like how pickled ginger is used in East Asian countries. Many people like them in an antipasto or as hot dog toppings.

You could also play on this onion’s sweetness. These onions won’t overpower, but they will enhance the flavor of dishes that you like and really add a crunchy, sweet note to an otherwise salty dish.

They will be good with any kind of seafood or in something like a poke to balance out the saltiness.


Spanish onions and sweet onions are very different from the rest of the onion family. As such, they can be used to create and match different flavor profiles that you wouldn’t have thought possible with the other kinds of onions.

If you have never used them before, give them a go. You may surprise yourself.

Jess Smith