Make the dough: Add the flours, yeast, salt and vital wheat gluten into a 6-quart round container or bowl. Whisk ingredients to combine.
Add water and mix with a Danish dough whisk or wooden spoon until fully incorporated, forming a wet and shaggy dough.
Cover loosely (leave lid open a crack). Allow to rise for two hours at room temperature. The dough will rise and then begin to collapse. Refrigerate for at least 2 hours, and use over the next 14 days, tearing off one-pound loaves as you need them.
On baking day, cut off 1 pound (454g, grapefruit-sized) piece of dough using a serrated knife or a kitchen shears.
Quickly shape a loaf by folding the edges under while turning the dough ball until you get a smooth ball. Place ball on lightly floured surface, lightly roll to desired final shape (oval, round, etc..). Try to not deflate the dough.
Cover dough loosely with plastic wrap and let it rest on a pizza peel covered with cornmeal or parchment paper for about 90 minutes.
Preheat the oven to 450°F (230°C), with a baking stone placed on a middle rack. Place an empty broiler tray for holding water on any other rack that won’t interfere with rising bread.
Just before baking, use a pastry brush to paint the top with water and sprinkle with seed mixture.
Slash the loaf with 1/2-inch deep parallel cuts across the top, if desired. Slide onto the hot stone and carefully pour 1 cup of hot tap water into the broiler tray. This creates steam for a nice crusty loaf.
Bake for 30 minutes. Remove from parchment paper, cool on wire rack.