Normally smaller than its western or European counterpart, and a member of the onion family, Red Onion has a brighter reddish colour than a purple onion (Bermuda onion) and definitely a sharper onion tang than its purple or brown cousins. Hom-daeng (onion-red, literal translation from Thai) have a purplish-red outer paper skin, and a generally stronger smell, a more pungent aroma than the yellowish-orange variety, which is milder in scent and sweeter to the taste.

Red Onions help to dispel intestinal gas, aide digestion and reduce discomfort in urination. They are also widely used as a regulatory aid for the menstrual cycle, and as part of an armamentarium in effectively fighting the common cold. Thai Red Onions are often called shallots, and their zesty red-white inner rings are used for soups, fried dishes, a sparky uncooked additional relish added to other near-finished dishes and as major, basic ingredients for pastes, gravies, sauces and vegetable dishes.

Frequently used as an essential primary pickling basic, with other spices added to contrast or augment the onion flavour, such as peppers and green tomatoes. Also widely seen is the chopping of the onion into fine, thinly diced bits of onion which are then deep-fried and added to condiments or soups as is, or ground into paste after frying.

Red Onions are used extensively in Persian, Indian, Cambodian, Indonesian, Lao and Malaysian cooking, and tend to be a bit more expensive than other local onion varieties, at least in part due to their milder, sweeter flavour and aroma. Sometimes they are grown, harvested, sliced, dried and then packed for market, in which case end-users often soak a batch for a day or two, to reduce the pungency of the shallot/onion.