If You’re a Toasted-Bagel Lover: The Slice-Then-Toast
The Method: Easy. Just slice your stale bagel in half and toast it as you would a fresh bagel.
The Advantages: Your bagel comes out very much like a standard toasted bagel.
The Disadvantages: Your bagel comes out very much like a standard toasted bagel, which is to say, suboptimal.
I strongly believe that the very best bagels should not be toasted, as toasting removes the exciting contrast between the thin, crackly exterior and the chewy, dense center. You can read more about my theory in my Good Bagel Manifesto; I have a lot to say on the matter. A fresh bagel should never be toasted, but slicing-then-toasting is not a bad option for a day-old bagel that needs resuscitating.
But we can do better.
For Stale, but Not Dry Bagels: The Whole-Bagel Toast
The Method: Place the entire intact bagel into the toaster oven, or a regular oven preheated to 375°F, for four to five minutes.
The Advantages: So long as your bagel has been stored in an airtight container (a zipper-lock bag in the fridge works fine) and has been stored for no more than about three days, this will very nicely reverse the staling process, delivering a bagel with the same crisp crust and chewy interior you’d expect straight from the bagel shop. It works equally well for frozen-then-thawed bagels.
For Stale and Dry Bagels: The Dip-and-Heat
The Method: Dip your bagel in hot water, then toast it whole.
