01 - Combine the active sourdough starter, lukewarm water, and sugar in a large mixing bowl. Stir thoroughly 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 with a wooden spoon or dough whisk until a shaggy, rough dough forms and no dry flour remains visible.
03 - Turn the dough onto a lightly floured work surface. Knead vigorously for 8 to 10 minutes, using the heel of your hand to push the dough forward and folding it back. Incorporate the vegetable oil during the final 2 minutes of kneading until the dough becomes smooth, elastic, and slightly tacky.
04 - Gently flatten the dough and scatter the fresh raspberries over the surface. Fold the dough over the berries carefully, pressing lightly to distribute them evenly while keeping the berries as whole as possible. The dough will appear sticky and develop a pink marbled appearance.
05 - Transfer the dough to a lightly greased bowl, turning once to coat all surfaces. Cover with plastic wrap or a damp kitchen towel. Let rise at room temperature for 6 to 8 hours until the dough has doubled in size.
06 - Turn the risen dough onto a lightly floured surface. Using a bench scraper or knife, divide the dough into 8 equal portions, approximately 4 ounces each. Work quickly to preserve the gas bubbles developed during fermentation.
07 - Form each portion into a smooth, tight ball by tucking the edges underneath. Poke a hole through the center of each ball with your thumb or index finger. Gently stretch and rotate the dough to create an even ring, ensuring the hole is approximately 2 inches wide.
08 - Arrange the shaped bagels on a parchment-lined baking sheet, leaving 2 inches of space between each. Cover loosely with a kitchen towel. Let proof at room temperature for 1 to 2 hours until slightly puffy, or refrigerate overnight for 8 to 12 hours for enhanced flavor development.
09 - Position an oven rack in the center position. Preheat the oven to 425°F, ensuring it reaches temperature before boiling the bagels.
10 - Pour 12.7 cups of water into a wide, deep pot and bring to a rolling boil over high heat. Stir in the honey or barley malt syrup until dissolved. Add baking soda if using for extra chewiness.
11 - Carefully lower 2 to 3 bagels into the boiling water, being careful not to overcrowd the pot. Boil for 45 to 60 seconds, then flip using a slotted spoon and boil the second side for an additional 45 to 60 seconds. Remove and drain briefly over the pot before returning to the baking sheet.
12 - Immediately after removing each bagel from the water, sprinkle with Demerara sugar or poppy seeds while the surface is still wet to ensure proper adhesion.
13 - Place the baking sheet in the preheated oven. Bake for 22 to 25 minutes until the bagels are deep golden brown, rotating the pan halfway through for even browning. The internal temperature should reach 200°F when fully baked.
14 - Transfer the baked bagels to a wire cooling rack. Let cool completely for at least 30 minutes before slicing to allow the crumb structure to set properly.