makes 12 bagels; recipe adapted from Maurizio Leo at The Perfect Loaf
Mix starter, flour, and water in a pint sized container. Cover loosely and let sit at room temperature overnight.
Mix the flour, water, levain, malt powder, sugar, and salt in a large mixing bowl with a dough hook until the dough comes together and then mix for 5 more minutes on medium speed.
Start 3 hours of bulk fermentation at warm room temperature with the dough bowl covered (use a towel, plastic wrap, or a bowl cover). About every 30 minutes, 30/60/90, do a set of "stretch and folds", either in the bowl or by removing dough from the bowl and doing it on the counter.
How to do a set of stretch and folds in the bowl: Wet your hands and starting at the "noon" position of your bowl, scoop the dough from the bottom of the bowl up and fold it over towards the middle of the dough ball. Repeat this every quarter turn around the bowl—from "noon" to "3 o'clock" bottom stretch to middle, "6 o'clock", "9 o'clock"—one complete trip around the clock equals one set of stretch and folds. Aim for at least 3 stretch and folds within the 3 hour bulk fermentation time but you can do it as frequently as every 30 minutes for a total of 6 times.
After bulk fermentation, weigh your dough and divide by 12. Portion into equal amounts and roll each into a rope, wrap it around your knuckles and palm of your hand to shape—check Maurizo's photos and/or YouTube bagel shaping.
Sprinkle cornmeal on a sheet pan. Place each shaped bagel on the cornmeal covered sheet pan. Loosely cover the bagels with lightly oiled plastic wrap—not overly tight so that the bagels have some room to rise.
Now is the time to either transfer the sheet pan to the refrigerator to retard the fermentation overnight or set the sheet pan in a warm place to proof for 2–3 hours (sometimes I go to 4 hours, it just depends...if they proof to a puffier state they make puffier bagels, not as dense.)
If you have a baking stone, set that in on the middle rack of your oven, if not don't worry about it. Preheat oven to 475°.
Set a large stockpot of water to boil.
If you did an overnight retard, remove the sheet pan of bagels from the refrigerator, otherwise your room temperature proofed bagels are ready to go. Once water comes to a boil, drop in the bagels (4 at a time works for the size of my pot) and boil 40 seconds on side one, flip, and 40 seconds on side two. Scoop bagels out using a strainer or slotted spoon and transfer to a Silpat-lined or parchment-lined sheet pan for baking, 6 per sheet pan. This is the time to top your bagels if you are going for something other than plain.
Bake bagels for 15 minutes at 475°, lower temperature to 450° for final 5 minutes. Transfer to a wire rack to cool completely.