While typically served as a side dish, onion rings are often eaten by themselves.

[2] The earliest recipe for onion rings dates back to 1802, when British food writer John Mollard published The Art of Cookery Made Easy and Refined.

It called for cutting onions into slices, dipping them into a batter including Parmesan cheese, and deep-frying them in lard.

[3] Many recipes for deep-fried onion slices or rings are found starting in the early 20th century.

There are various processes: The cooking process decomposes propanethial oxide in the onion into the sweet-smelling and tasting in bispropenyl disulfide, responsible for the slightly sweet taste of onion rings.