01 - Combine active sourdough starter, lukewarm water, and sugar in a large mixing bowl. Stir continuously until sugar crystals fully dissolve into the mixture.
02 - Add bread flour, whole wheat flour, and sea salt to the starter mixture. Stir with a wooden spoon until a shaggy, sticky dough forms with no dry flour visible.
03 - Turn dough onto a lightly floured work surface. Knead firmly for 8 to 10 minutes, pushing dough away with heels of hands and folding back toward you. Drizzle vegetable oil over dough during the final minute of kneading and work until fully incorporated and surface feels smooth and elastic.
04 - Gently fold raspberries into the dough using a light touch to preserve berry integrity. Dough will appear sticky with a marbled pink pattern throughout.
05 - Place dough in a lightly greased bowl, turning once to coat all surfaces. Cover tightly with plastic wrap or a damp kitchen towel. Let rise at room temperature for 6 to 8 hours until dough has doubled in size.
06 - Turn risen dough onto a lightly floured surface. Using a bench scraper or knife, divide dough into 8 equal portions, approximately 4 ounces each.
07 - Form each portion into a smooth ball by tucking edges underneath. Poke a thumb through the center of each ball and gently rotate and stretch to create a 2-inch hole, forming the classic bagel shape.
08 - Arrange shaped bagels on a parchment-lined baking sheet, leaving 2 inches of space between each. Cover loosely with a clean kitchen towel. Let proof at room temperature for 1 to 2 hours, or refrigerate overnight for deeper sourdough flavor development.
09 - Position oven rack to center position. Preheat oven to 425°F.
10 - Bring 12 cups water to a rolling boil in a wide, deep pot. Stir in honey or barley malt syrup until dissolved. Add baking soda now if using for extra chewiness.
11 - Working in batches of 2 or 3, carefully lower bagels into boiling water. Boil for 45 to 60 seconds per side. Bagels should float and surface will appear slightly blistered. Remove with a slotted spoon, allowing excess water to drain briefly, then return to parchment-lined baking sheet.
12 - Immediately after boiling, sprinkle Demerara sugar or press poppy seeds onto the wet bagel surfaces while tacky for best adhesion.
13 - Bake bagels for 22 to 25 minutes until deep golden brown with a shiny, crackled crust. Rotate baking sheet halfway through baking for even color.
14 - Transfer baked bagels to a wire cooling rack. Let cool completely for at least 30 minutes before slicing to prevent gummy texture.