Onion is a vegetable which is almost like a staple in Indian food. This is also known to be one of the essential ingredients of raw salads. They come in different colours like white|red or yellow and are quite in demand in cold salads and hot soups.
You can dice|slice or cut it in rings and put it in burgers and sandwiches. Onions emit a sharp flavor and fragrance once they are fried; it is due to the Sulphur compound in the vegetable. Onions are known to be rich in biotin.
Most of the flavonoids which are known as anti-oxidants are concentrated more in the outer layers|so when you peel off the layers|you should remove as little as possible.