Spanish Onions vs Red, White, Yellow & Sweet

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Spanish onions are a great source of pungent flavor and heady aroma. All cooked onions add flavors from tang to sweetness, and raw onions also offer a bit of crunch!

However, different onion varieties offer unique intensities, so a primer on onion strength is worth the study. In this guide you will learn everything you need to know about the most common types of onions.

Types Of Onions

Onions are the bulbous roots that build up in the soil under the fresh green onion tops during warm weather. They differ by color, shape and flavor.

Many onions are interchangeable in cooked dishes but add a unique flavor boost when raw.

White Onions

White Onions

White onions have a clean, mild flavor and work well for a light onion flavor in salads and on sandwiches.

They cook well, but don’t last as long in storage as yellow onions.

White onions tend to be lower in aroma than many other varieties, particularly red onions.

Yellow Onions

yellow onion picture

Yellow onions are the most commonly used onion in the United States.

They’re larger than white onions and develop a sweeter flavor when cooked, making them a great choice for caramelized onions.

However, when served raw, yellow onions can be harsh to some diners.

When looking for a great onion to serve raw, choose carefully among the Spanish onion vs yellow onion bins; your sandwich may deliver an unpleasant surprise if you grab the wrong one.

Red Onions

red onion picture

Red onions come from the same onion family as yellow onions but have anthocyanins in each layer of the onion flesh.

Red onions tend to have a more intense flavor and an especially pungent odor. Fresh red onions look great on a relish tray, but when cooked they will appear duller.

While red onions are generally available year round, if you’re looking for a good red onion substitute to serve raw, you can toss yellow onions in a bit of red wine vinegar.

Spanish Onions

Spanish Onions

Spanish onions are often stored right next to yellow onions in the grocery store. They’re also yellow and fairly large.

Spanish onions are simply yellow onions that are grown in a low sulfur soil, reducing the intensity of their flavor and letting the sweet starch come through when cooking.

Best Way To Serve Spanish Onions

Spanish onions are extremely versatile and work well both raw and cooked. These onions are quite large and low in sulfur, so the odor so commonly associated with raw onions in a salad or on a sandwich plate is not a concern.

However, Spanish onions are quite high in water, so they will and lose their crunch as they warm up. If possible, serve them on a chilled relish plate or in a cold salad bowl for best effect.

Spanish Onions Substitute

If you’re drawn to sweet onions, it may be that you don’t care for the harsher flavors often found in the standard yellow onions, or the strong aroma of red onions.

Sweet Vidalia Onion

For cooks who only want a bit of onion flavor, a white onion may be the best substitute in cooking.

If sweet Vidalia and Walla Walla onions are in season, you’re in luck!

When buying the more fragile summer sweet onions, storage and shelf life will be more limited. Purchase these onions in smaller batches and make plans to cook them quickly.

Many sweet onion varieties, both summer and storage onions, caramelize extremely well. There are several ways to caramelize onions, including placing them on a shish kebab skewer and grilling them. Enjoy!

Spanish Onions Vs Sweet Onions

What color is a sweet onion? Sweet onions are generally yellow. This can be confusing at the grocery store; sweet onions may be yellow, but not all yellow onions qualify as sweet!

Sweet onions such as the Vidalia or the Walla Walla are referred to as summer onions; in most parts of the United States, they are only available seasonally. These onions have very high water content and have a limited shelf life.

What is a Spanish onion? Spanish onions are known as storage onions. They contain less water than a storage onion, have a longer storage life, but have a sweeter flavor than a regular yellow or white onion.

Cooking & Handling Onions

Even a mild onion will sting your eyes when cooking. Per chemistry experts with Scientific American, all onions contain amino acid sulfoxides.

Any time you break the cell wall of an onion, a chemical reaction occurs that causes your eyes to tear.

Onions have high water content and tend to be very crisp; therefore, if you’re making a stew or soup, they need to go into the pot first so you can sauté and soften them.

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As onions cook down, they release their flavor into the fat and broth in the pot. Sweet and pungent onions behave the same when heat is applied.

Shopping, Storage and Cost Concerns

Per authorities with the National Onion Association, whole onions should be stored in the refrigerator. One of the benefits of onions is that most non-summer onions can be stored for quite a long time.

However, once you cut into an onion, they will begin to wilt and may rot. This will not be a mystery; rotten onions have a very strong aroma.

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When deciding between a yellow vs white onion, it’s important to note that white onions are much crisper and less intense in flavor and aroma. Store cut onions in a zippered plastic storage bag and be certain to use them within seven days.

If you don’t care for onion flavor and wind up cutting a lot of onions in half, be aware that white onions are smaller, milder, and can often be used completely, reducing the amount of kitchen waste.

Final Thoughts

Onions are an ancient cultivated vegetable; the Vedic writings of India reference them, as do the writings of ancient Egypt and Sumeria.

This bulbous vegetable is generally quite cost-effective, offers hearty flavor both raw and cooked, and stores well.

While not all onions are to everyone’s taste, most cooks can generally find an onion that will serve, particularly in cooked dishes.

Written By Tara Williams

Tara is a food writer that has been editing and authoring articles for KitchenSanity since its founding. Her writing offers personal experience from experimentation with food and recipe creation. If you’re looking for simple tips, she will make your journey in the kitchen straightforward with a dash of fun.