Today, I decided to make Gyros for dinner and was looking up recipes for the sauce and what to add in the Gyro itself. Most recipes called for onions, not specifying which to use.  I got curious about why you use certain onions for certain things and can they be interchangeable.  I found the following information useful.

Wonder why some recipes call for a particular kind of onion and whether another can be substituted in its place?

All these onions vary slightly in flavor, texture, and color, but can usually be substituted for one another. In terms of cooking, they will all behave the same in the pan.

When buying onions, go for ones that feel heavy in your hand and firm. Avoid soft onions or ones that have a sharp oniony odor before peeling. These are indications that the onion is old. Except for sweet onions, all these onions can be stored for several weeks in a cool, dark pantry or cupboard.

Yellow Onions  This is the all-purpose onion, and it’s the one we use most often. Yellow onions have a nice balance of astringency and sweet in their flavor, becoming sweeter the longer they cook. They are usually fist-sized and have a fairly tough outer skin and meaty layers. Spanish onions are a particular kind of yellow onion and we find them to be slightly sweeter and more delicate in flavor.

White Onions – These onions tend to have a sharper and more pungent flavor than yellow onions. They tend to be more tender and have a thinner, more papery skin. They can be cooked just like yellow onions, but we like them minced and added to raw salsas and chutneys.

Sweet Onions – Walla Walla and Vidalia are the most common kinds of sweet onions. These onions lack the sharp, astringent taste of other onions and really do taste sweet. They are fantastic thinly sliced and served in salads or on top of sandwiches. They can range in color from white to yellow and often have a flattened or squashed appearance. Sweet onions tend to be more perishable and should be stored in the refrigerator.

Red Onions – With their deep purple outer skin and reddish flesh, these are really the odd guys out in the onion family. They are fairly similar to yellow onions in flavor, though their layers are slightly less tender and meaty. Red onions are most often used in salads, salsas, and other raw preparations for their color and relatively mild flavor. The lovely red color becomes washed out during cooking. If you find their flavor to astringent for eating raw, try soaking them in water before serving.

Onions are a garden favorite and can be eaten raw, in salsas and salads, and cooked into your favorite recipes. Home gardeners can choose from onion varieties that are mildly sweet to pungent. Because onions are affected by the amount of light they receive, some grow better in the North, while others perform better in the South. Short-day onions begin forming bulbs when daylight lasts 10-12 hours and are often the sweetest and best for eating raw. They’re most often grown in the South. Long-day onions begin forming bulbs when daylight lasts 14-16 hours. They are usually pungent, often store well for many months, and are usually grown in the North. Day-neutral onions are a cross of the two types. Onions can be started from seeds, sets, and plants.

Shallots

Shallots have a subtle flavor that is much milder than onions or garlic and are a favorite of gourmet cooks. Their flavor really shines when sautéed in butter or olive oil. Like green onions, their green shoots and bulbs are edible and the green shoots can be used as a green onion or scallion substitute. While shallots can be grown from seed, growing them from sets is often easiest. After harvest, cured bulbs can be stored for up to six months.

Leeks

Leeks look like overgrown green onions but have a milder, more delicate flavor than onions. The white base and green stalk are used for cooking in creamy soups, fresh, stocks and more. Leeks can be direct seeded outdoors or started indoors and transplanted into the garden. Thinning during the growing allows the plant to grow much larger. After harvest, leeks can keep in the refrigerator for up to 2 weeks—or they can be dried for storage.

Remember…

Onions, shallots, and leeks are not considered interchangeable when it comes to cooking, even though some blogs and websites might say they are interchangable. Make sure you use whichever your recipe calls for, as the distinct flavor of each may alter the taste of your dish.

Do you have a favorite kind of onion?