01 - In a large bowl, combine the active sourdough starter, lukewarm water, and sugar. Stir continuously until the sugar completely dissolves and the mixture is uniform.
02 - Add bread flour, whole wheat flour, and fine sea salt to the starter mixture. Mix thoroughly until a shaggy, rough dough forms and all dry ingredients are incorporated.
03 - Turn the dough onto a lightly floured surface and knead for 8 to 10 minutes until smooth and elastic. Drizzle the vegetable oil over the dough during the final minute of kneading and work it in completely.
04 - Gently fold the fresh raspberries into the dough, handling lightly to keep the berries as whole as possible. The dough will appear sticky and have a marbled pink appearance.
05 - Transfer the dough to a lightly greased bowl, cover with plastic wrap or a clean towel, and let rise at room temperature for 6 to 8 hours until doubled in size.
06 - Turn the risen dough onto a lightly floured surface. Divide into 8 equal portions using a dough scraper or knife.
07 - Shape each portion into a smooth ball. Poke a hole through the center of each ball with your finger, then gently stretch and rotate to form an even ring with a 2-inch diameter opening.
08 - Place the shaped bagels on a parchment-lined baking sheet, cover with a clean towel, and let proof for 1 to 2 hours until slightly puffed. For enhanced flavor development, refrigerate overnight at this stage.
09 - Preheat the oven to 425°F approximately 30 minutes before baking.
10 - Bring 12 quarts of water to a rolling boil in a wide, deep pot. Stir in the honey or barley malt syrup until dissolved. Add baking soda now if using for extra chewiness.
11 - Working in batches, carefully place bagels into the boiling water. Boil for 45 to 60 seconds per side. Remove with a slotted spoon, allowing excess water to drain off, and return to the parchment-lined baking sheet.
12 - Immediately sprinkle the tops of the wet bagels with Demerara sugar or poppy seeds while the surface is still tacky from boiling, ensuring good adhesion.
13 - Bake for 22 to 25 minutes until deeply golden brown and the crust is firm to the touch. Rotate the baking sheet halfway through for even browning.
14 - Transfer the baked bagels to a wire rack and let cool completely for at least 30 minutes before slicing or serving to allow the crumb structure to set.