Onion rings are best served fresh from the fryer for the most tender insides and crunchy crust. However, if you're in a pinch and need to make them ahead of time or want to store leftovers for later, you can refrigerate or freeze and reheat them when you are ready.u003cbr/u003eu003cbr/u003ePop the onion rings into an airtight container and place them in the refrigerator for up to three days or freeze for about three months. To reheat, you can bake the onion rings in the oven or air fryer.