Normally you take a knife slice a bagel down the middle and you end up with 2 half's but part of that action ends up cutting both sides of the hole at the same time.
Instead take a knife cut to the center but not the other side then as you cut around the edge rotate the cut so by the time your around the full bagel the knife is upside down. If you picture it at one point knife handle is on the above the bagel and after a little while it's below the bagel. The only trick is to make you cut line up when your done.
Instead take a knife cut to the center but not the other side then as you cut around the edge rotate the cut so by the time your around the full bagel the knife is upside down. If you picture it at one point knife handle is on the above the bagel and after a little while it's below the bagel. The only trick is to make you cut line up when your done.