Red Onion, Allium Cepa Royalty-Free Stock Photo

Red onions also known as purple or blue onions are cultivars of the onion, Allium cepa, and have purplish-red skin and white flesh tinged with red. Red onions tend to be medium to large in size and have a sweeter flavor than white or yellow onions. Red onions get their reddish-purple color from anthocyanins, a compound that gives them a red, purple, or blue hue.