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General Description: The mature onion (Allium cepa) is a white, yellow, or red bulb that is pungent when raw and sweet when cooked. The diverse onion family probably originated in central Asia, although onions now grow throughout the world. Onions have been eaten and cultivated since prehistoric times, when they were raised in ancient Mesopotamian gardens and appeared in Egyptian tomb paintings.

Fleshy layers attached at the root end are covered with layers of thin paper skin that develop as the onion matures. The bite of raw onions is due to sulfur compounds. When an onion is cut, the crushing of the cells and contact with air releases allicin—which in turn causes one’s eyes to water.

Onions are of two general categories: spring/summer fresh bulb onions and storage onions. Fresh onions can be yellow, white, or red, with varied shapes—flat, top-shaped, round, and long. These mild, juicy onions have thin, light-colored skin and are often used raw. Storage onions are yellow, white, or red but almost always round. These moderate to strong, full-flavored onions are noted for their storing, shipping, and cooking qualities. Several layers of thick, dark skin protect them. Storage onions are typically much harsher when eaten raw, though they may be the sweetest when cooked. Picklers, pearls, creamers, boilers, standards, and jumbos are simply size names for the same variety of onion, planted differently and picked at different times.

Most sweet onions are hybrids. With a sugar content that is actually lower than other onions, they are not truly sweeter than common onions. However, they are milder, having less pyruvic acid, which imparts “heat” to onions. They are also exceptionally juicy with large thick rings and thin skins separating the layers. The sweet onion’s delicate nature requires that it be harvested by hand, thoroughly dried, and treated gently during grading and packaging.

There are many different kinds of onions. Apaz onions are wild onions that resemble pearl onions topped with a green stalk. Bermuda onions come in red, white, and yellow and all are mild. The Bermuda onion may actually be of Italian origin. Boiling onions are thin-skinned, small onions meant for cooking whole in stews. Cipollini are distinct, flattened flying saucer-shaped onions from Italy. They are unusually rich and sweet but more perishable than round pearls. Green onions (also called scallions) are pulled while the tops are still green and before a large bulb has formed.

Italian red onions are flattened with definite ridges and thick layers. The inner skin layers are deep purple. They don’t store well but have sweeter flavor and crunchier texture than other red onions. Pearl onions are small because they are planted tightly together and are picked early. They are as pungent and storable as larger onions. Spanish onions are a large category of generally mild globe onions. They are the most common onion at the market and may be found in very large sizes. Spring onions have formed bulbs but their tops are still green. They are sweet and sharp and must be used quickly.

Vidalia onions are Georgia-grown and known for their sweet, mild flavor, which is partly due to the unique combination of soils and climate in their production area. Maui, Hawaii, is the home of the famous sweet Maui onion. Walla Walla sweets were brought to Walla Walla, Washington, from Corsica at the beginning of the 20th century. These “French” onions were developed over several generations to be exceptionally sweet, jumbo-sized, and round.

Tropea in Calabria, Italy, is famous for its pungent, football-shaped, red torpedo onion. The history of the Tropea onion in Italy can be traced back to its introduction by the Phoenicians around 2,000 years ago. White onions are mild in flavor with papery white skins. They can be quite large and round and are good both raw and cooked.

Season: Many onions are available year-round. Apaz onions from Oregon peak in June. Italian red onions are in season April through August. Pearl onions are in season beginning with whites in July and followed by the red and gold pearls. Availability typically continues through March. Spanish sweets will be found January through March and August through December. Vidalia onions are harvested from late April through mid-June. Retailers usually have fresh Vidalia onions available through mid-July, although with modified atmosphere long-term storage, they are now available much of the year. Walla Walla onions are best in June and July.

Purchase: Look for onions that are dry, firm, and shiny with a thin skin. The necks should be tightly closed with no sprouts. The outer skins should be papery and can be loose. Good-quality pearl onions will be a uniform size and have firm, clear skin with no bruises or blemishes. Choose scallions with medium-sized necks that are well blanched 2 to 3 inches above the root.

Avoid: Onions with green sprouts will taste bitter. Avoid onions with dark patches and soft spots. Examine the sprout end of Italian red onions: It is often sunken and this is where the first signs of spoilage begin. Avoid any onions with soft, deeply sunken or yellow tops and any black mold. Avoid pearl onions that are too big or blemished, or have soft or moldy spots.

Storage: Onions should be stored in a loosely woven bag—not plastic—in a cool, dark, dry, and well-ventilated area. For long-term storage wrap each onion separately in foil and refrigerate. Do not store onions under the sink or with potatoes because potatoes give off moisture that can cause onions to spoil. Pearl onions should be kept away from fluorescent lighting, which turns them green.


  1. To lessen crying, chill an onion before chopping and use a very sharp knife.
  2. Peel away the papery outer skin and any blemished layers. If the onion will be chopped, trim off the top and peel the outer layers while leaving the root end whole. (The root end contains the most sulfuric compounds.)

Note: To cut down on sharpness when serving raw onions, place in a bowl of ice water for 30 minutes and then drain.

Serving Suggestions: Marinate pearl or cipollini onions and thread on kebabs for grilling. Roast whole small onions at high heat till they are caramelized (peel before or after roasting). Top sandwiches, salads, or burgers with slices of red, white, or yellow sweet onion. Make pink onion pickles by soaking sliced red onions in ice water and vinegar until the onions turn pink, then drain and serve.

Flavor Affinities: Onions complement any savory food.

from Quirk Books: