
Common onions are normally available in three yellow, brown, red, purple and white colors.. Yellow or brown onions (also called red) are full-flavored and are the onions of choice for everyday use. Yellow onions turn a rich, dark brown when caramelized and give French onion soup its sweet flavor. The red onion (also called purple) is a good choice for fresh use but can be also good for grilling. White onions are widely used in classic Mexican cuisine, and have a particularly sweet flavor when sauteed.