The yellow onion or brown onion is a variety of dry onion with a strong flavor. White inside, its layers of papery skin have a yellow-brown color.It has a rich onion taste and is fit for food dishes like French onion soup. Yellow onions are typically available throughout the year. This onion is higher in sulfur than the white onion, which gives it a stronger, more complex flavor.A dozen varieties of yellow onion are grown, following the time of year. They vary in nutritional content.