popularized in the US
by Outback Steakhouse
, generically known as an onion blossom
A Bloomin' Onion is a large onion which has been cut into spears still attached to the base with a gadget that looks like a wheel with knife blades for spokes. (If you're playing along at home, quarter the onion with top-down slices, leaving a half-inch of uncut onion at the base. Then divide the quarters, etc., until the onion blades are about as wide as a finger.)
The onion is then breaded and deep-fried, and served with a creamy horseradish sauce. (I'm guessing mayonnaise, horseradish and ketchup.)
A heart attack on a plate, but oh so tasty. Available under one name or another in various Tchotchkies-type restaurants, and even starting to show up in stadiums.