A vague discussion (vaguels?) contributed by Mycroft (who takes no responsibility should this result in disaster).

From memory, bagels are made from a pretty ordinary pizza/bread dough. Once proved you make donut shapes, boil them for about 5 minutes, then throw them in the oven until they're done. Be warned though: I never made them particularly well and I doubt my fading memory of the procedure will improved things.

...and now into specifics, by Fenchurch the Honky-Tonk Thumper

I don't think they're made from normal dough: I think they're made from Kosher dough (according to Jewish Law) by a specialised Rabbi. And to be precise, the donut shape is a ring (I associate English doughnuts with a roll-shaped lump of dough).

You can also sprinkle with poppy or sesame seeds, or make with onion-dough or apple dough.