The Red onion is a bulb onion grown from seed or sets (small bulbs less than one inch in diameter). It has a burgundy wine-colored sheath that protects its ruby and white ringed, coarse flesh. Red onion's flavor ranges from sweet to pungent depending on its age, particular variety or how much sulfur was in the growing soil or in the fertilizer used. It can grow up to 6 inches in diameter if harvested at its latest point of maturity.
Red onions are available year-round.
Onions vary in colors shape, flavor and sizes, however all onions can be categorized as either spring/summer varieties, or storage varieties. The Red onion is classified as a spring/summer variety as it has a thin protective layer whereas storage onions have multiple protective layers which allows them greater time to be stored and less chance of bruising. Mature onions are ready for harvesting when their green tops wither, fall over and begin to turn brown. This occurs approximately six months after planting.
Red onions have a high polyphenol content, including a rich concentration of flavonoid polyphenols. Among the flavonoids, they also provide a particularly large amount of quercetin. The highest concentrations of quercetin occur in the outermost rings and in the part closest to the root. Quercetin provides antioxidant properties that are known to have preventative and curing properties related to cancer, heart and digestive illnesses.
Red onions may be used in recipes calling simply for onions but they are used principally as a main ingredient alongside a few other supporting ingredients as their bold flavor will generally dominate any dish they are in. Red onions are heavily utilized as a sandwich onion, yet they can be roasted, grilled, braised, caramelized, fried and even pickled. Complimentary pairings include foods rich in fat such as cream, melting and fresh cheeses, eggs, avocados, olive oil and nuts, grilled meats, acidic ingredients such as citrus, vinegars and tomatoes, vibrant herbs including basil, cilantro, parsley and tarragon and warming spices including cumin, cayenne, cinnamon and star anise.