Scallions are re-usable! By re-usable, I mean that they actually can be used at least twice. After the first cutting of the green hollow part of the onion, you can place the white portion in about 2 inches of water and place them in a sunny window seal then watch them take off growing. Change the water daily and you will find that they grow very quickly, about an inch a day.
Almost every culture uses scallions. They are much more mild than the common onion. My grandmother, Meme, ate them whole as a condiment on the side of her main dish. They are used in many Asian and Vietnamese dishes as well as Mexican dishes.
The white part of the scallion is used for medicinal purposes as well as a culinary purposes. Scallions are used as an anti-septic, an an-antifungal, anti-bacterial, and expectorant. Scallions treat the the respiratory tract therefore treating the common cold. It is hard to believe, but scallions even help indigestion and insomnia. I better go to the garden right now, pull up some scallions and get to munching! Maybe I will get better sleep tonight.
Oh, if purchasing scallions, look for ones that have a large root system. These will grow much better. Happy munching.