Stir ice water and malt syrup together in 2-cup liquid measuring cup until malt syrup has fully dissolved. Process flour, wheat gluten, and yeast in food processor until combined, about 2 seconds. With processor running, slowly add ice water mixture; process until dough is just combined and no dry flour remains, about 20 seconds. Let dough stand for 10 minutes.
Add salt to dough and process, stopping processor and redistributing dough as needed, until dough forms shaggy mass that clears sides of workbowl (dough may not form one single mass), 45 to 90 seconds. Transfer dough to unfloured counter and knead until smooth, about 1 minute. Divide dough into 8 equal pieces (3 1/2 ounces each) and cover loosely with plastic wrap.
Working with 1 piece of dough at a time and keeping remaining pieces covered, form dough pieces into smooth, taut rounds. (To round, set piece of dough on unfloured counter. Loosely cup your hand around dough and, without applying pressure to dough, move your hand in small circular motions. Tackiness of dough against counter and circular motion should work dough into smooth, even ball, but if dough sticks to your hands, lightly dust your fingers with flour.) Let dough balls rest on counter, covered, for 15 minutes.
Sprinkle rimmed baking sheet with cornmeal. Working with 1 dough ball at a time and keeping remaining pieces covered, coat dough balls lightly with flour and then, using your hands and rolling pin, pat and roll dough balls into 5-inch rounds. Starting with edge of dough farthest from you, roll into tight cylinder. Starting at center of cylinder and working toward ends, gently and evenly roll and stretch dough into 8- to 9-inch-long rope. Do not taper ends. Rolling ends of dough under your hands in opposite directions, twist rope to form tight spiral. Without unrolling spiral, wrap rope around your fingers, overlapping ends of dough by about 2 inches under your palm, to create ring shape. Pinch ends of dough gently together. With overlap under your palm, press and roll seam using circular motion on counter to fully seal. Transfer rings to prepared sheet and cover loosely with plastic, leaving at least 1 inch between bagels. Let bagels stand at room temperature for 1 hour. Cover sheet tightly with plastic and refrigerate for 16 to 24 hours.
One hour before baking, adjust oven rack to upper-middle position, place baking stone on rack, and heat oven to 450 degrees.
Bring 4 quarts water, sugar, and baking soda to boil in large Dutch oven. Set wire rack in rimmed baking sheet and spray rack with vegetable oil spray.
Transfer 4 bagels to boiling water and cook for 20 seconds. Using wire skimmer or slotted spoon, flip bagels over and cook 20 seconds longer. Using wire skimmer or slotted spoon, transfer bagels to prepared wire rack, with cornmeal side facing down. Repeat with remaining 4 bagels.
Place sheet with bagels on preheated baking stone and pour 1/2 cup boiling water into bottom of sheet. Bake until tops of bagels are beginning to brown, 10 to 12 minutes. Using metal spatula, flip bagels and continue to bake until golden brown, 10 to 12 minutes longer. Remove sheet from oven and let bagels cool on wire rack for at least 15 minutes. Serve warm or at room temperature.
This recipe requires refrigerating the shaped bagels for 16 to 24 hours before baking them. This recipe works best with King Arthur bread flour, although other bread flours will work. Vital wheat gluten and malt syrup are available in most supermarkets in the baking and syrup aisles, respectively. If you cannot find malt syrup, substitute 4 teaspoons of molasses. The bagels are best eaten within a day of baking; fully cooled bagels can be transferred to heavy-duty zipper-lock bags and frozen for up to one month.