[SeeAPenny]

Onions and peppers are among the easiest veggies to freeze, because they need no blanching first. Simply dice them up (or use a food processor), and freeze. It's best to try to freeze them flat first, like on a cookie sheet or a plate, and then transfer them to a freezer bag once frozen. That way, the pieces don't stick and freeze together in a big clump. In the summer when I have access to cheap or free peppers and onions, I process and freeze them this way in large quantities because they are so handy to have (and because peppers are so expensive to buy out-of-season). I really don't know how long they can be stored in the freezer, several months at the very least I should think.