I'm nutritionist, Siona Sammartino, and this is "how to core and chop an onion." Onions are a popular vegetable, used in recipes, as they serve as a base vegetable, and what we like to call an aromatic in the culinary world. They're also high in sulfur compounds, which makes them great for boosting the immune system. So, here's how I core and chop it up. A little onion anatomy for ya, before we get started. We have the top, the root end, and what I like to call, the waistline of the onion. Begin by removing the tip of the onion to create a flat, sturdy surface for cutting. Then, cut the onion from root to top to expose the core. From here, peel back the papery skin layer, and one additional layer of the onion, if it appears papery, or has any blemishes. To create half-moons, simply cut thin slices in a direction that is parallel to the core. Stop about a quarter to a half an inch from the core, and you'll notice that the core has now been easily removed and left behind. If you'd rather dice your onion, place your freehand firmly on the top of the onion, and fan your fingers upward and away from the blade. This helps to make this safe. Then, make two or three cuts into your onion. And, from here, make horizontal cuts, being sure to keep those fingers tucked back. And, then, finish it up by making vertical cuts along the onion. Your onion is now ready for recipes, and is a perfect vegetable, any time of year, but especially useful during cold and flu season. And, that's how to core and chop an onion.